context: The movie opens where Back to the Future left off: October 26, 1985. Marty (Michael J. Fox) opens the garage door and sees his 4X4, the one he longed for in Back to the Future. Jennifer Parker (now played by Elisabeth Shue) asks for a ride. Marty tells her that she is a sight for sore eyes, and wants to look at her. She says that he's acting like he hasn't seen her for a week. She asks if he's OK. When he sees his mom and dad, he says yeah.As they are about to kiss, there are three sonic booms and the DeLorean appears and screeches to a stop in the driveway. Doc (Christopher Lloyd) jumps out and smashes into one of the trash cans. He frantically tells Marty that he has to come back with him. Marty sees his strange goggles and asks, "Where?" Doc answers, "Back to the future!" Doc rummages in the garbage can, and then grabs some banana peels and a discarded beer can. Marty asks him what he's doing, and Doc hastily claims he needs fuel. He opens the attached Mr. Fusion Home Energy Reactor, and puts the banana peels in, topping it off with the beer can and the leftover beer inside it. Doc tells Marty to get in the car, but Marty protests, saying he just got here, and Jennifer and he are going to take the new truck for a spin. Doc tells Marty that they'll take her along, because this concerns her too.Marty wonders what happens to them in the future, Doc hesitates for a moment, before replying that they come out fine, but that something has to be done about their kids. After they get in, and Doc backs up into the street, Marty tells Doc that he had better back up, because they don't have enough road on the street to get up to 88 MPH. Doc quips, "Roads? Where we're going, we don't need roads." As Doc is starting up the car, Biff Tannen (Thomas F. Wilson) comes out of the house, and wants to show Marty the matchbooks he just got printed up for his auto detailing service, just in time to see the DeLorean fly away and vanish in a flash of light. "A flying DeLorean?" he asks, in disbelief.They reappear in the year 2015, and immediately find themselves flying against traffic. Doc crosses to the right "lane". They descend into Hill Valley on October 21, 2015. Jennifer is confused, and Marty tells her they're in a time machine. She asks about their future, the wedding, and where they will live. Doc knocks her out with a sleep inducing "alpha rhythm generator." He tells Marty that when she wakes up she'll think it was a dream. He says he did that because she was asking too many questions about her future, and she's not essential to his plans.The DeLorean lands in an alley in the middle of a rainstorm. Doc tells Marty to wait five more seconds, and the rain stops right on the tick, as promised. Doc says they have an efficient weather service now, much more efficient than the postal service. When Marty gets out, Doc peels off a rubber mask, saying he went to a rejuvenation clinic and got a natural overhaul. He says they added 30 or 40 years to his life (but he looks the same.) They also replaced his spleen and colon. Marty asks about his own future, if he'll be a rich rock star. Doc warns Marty that no one should know too much about their future. He tells Marty to change his clothes. Meanwhile, Doc spies on Marty's future son Marty Jr. (also played by Michael J. Fox), saying they're precisely on schedule. The clothes Doc has given Marty have power laces on the shoes, and a self-adjusting fit on the jacket. Doc tells him to pull out his pants pockets, because all kids wear them like that today. He gives Marty an iridescent multi-colored cap like his son, then tells him to go into the Café '80s (one of those "not-well-executed nostalgic-themed restaurants") in exactly two minutes and order a Pepsi. A guy named Griff is going to show up and ask Marty whether he is in or out about "tonight's opportunity". Marty is to tell him he is out, say no, and come back immediately.Marty now asks what this has to do with his son. Doc shows Marty tomorrow's copy of USA Today, and Marty is shocked by what he reads: today, Martin McFly Jr. is going to be arrested for theft, and within 2 hours of his arrest, he will be tried, convicted, and sentenced to 15 years in the state penitentiary (the justice system works swiftly these days now that all lawyers have been abolished). To make matters worse, the next week Marty's daughter Marlene (also Michael J. Fox, in drag) will attempt to break her brother out and will get sentenced to 20 years in jail, causing a chain reaction that destroys Marty's entire family. Doc's alarm watch is late, but he will try to intercept the real Marty Jr. before he can get to the Café 80s. Before Marty goes, Doc warns him to be careful because Griff has "some short circuits in his bionic implants."When Marty reaches the town square, he notices a pond in the middle where the park, and parking lot, used to be. A car is in the robotic Texaco service station. The movie theater is showing "Jaws 19". Suddenly a hologram of a giant shark comes from the theater, swoops down on Marty and "bites" him, scaring him. He's not satisfied, that the shark "still looks fake." An electronic billboard advertises Wilson Hover Conversion Systems. Marty sees an antique shop, where he notices unusual items like a B&W; Macintosh computer, a lava lamp, and a Gray's Sports Almanac. The almanac lists sports results from the years 1950 to 2000.Marty goes into the Café '80s, which is full of nostalgic items from the 1980s. Several video screens are advertising the food & drink there; they are also the waiters. The screens use personalities from the 1980s: Michael Jackson, Ronald Reagan, and the Ayatollah Khomeini. They talk like Max Headroom. While waiting on Marty, Ronald and the Ayatollah talk at the same time, almost as if arguing. Marty tells them to stop, that he only wants a Pepsi; one quickly pops up.Biff, now an old man, walks to Marty, mistaking him for Marty Jr., and bopping him on the head with his cane that's topped by a small silver fist and tells Marty how he's going to flush his life down the toilet. Marty thinks Biff is talking about himself, and is confused. Biff knocks him on the head with his cane saying, "Hello! Anybody home?" Outside, Griff (also Thomas F. Wilson) lands his car. He comes in and angrily chews out his grandfather for not applying two full coats of wax to his car. Biff argues, but Griff makes him go outside and redo it. Marty asks Biff if he and Griff are related, and Biff knocks him on the head again before he leaves. Marty notices two boys (one played by a young Elijah Wood) turn on an antique shooting game. Marty offers to demonstrate, grabs the revolver control and shoots all the opponents, but they complain that the game is like a baby's toy because you have to use your hands; they leave. Marty Jr. peers in through the window. Unlike the real Marty, we see that his jacket sleeves are ill-fitting. He comes in and asks for a Pepsi. Marty panics and hides behind the counter. Griff and his gang (Ricky Dean Logan, Darlene Vogel, and Jason Scott Lee) come in.Griff confronts Marty Jr. in the typical Tannen way, and beats him. He asks Marty Jr. if he made a decision about "tonight's opportunity." Marty Jr. says it might be dangerous, that he has to discuss it with his father. Griff throws him behind the counter. Marty orders Marty Jr. to keep quiet; Marty Jr. faints. Marty now stands up as Griff demands he give the right answer. Marty gives a firm no, then departs. Griff calls Marty chicken, hiding a telescoping bat behind his back. Marty, being Marty, can't resist when someone calls him chicken. Just as he's saying such, Griff swings at Marty with his bat and misses, hitting a video waiter. When Marty puts up his dukes, Griff rises up another half foot with his implants. Marty tries to distract Griff & throws a punch which Griff easily catches. Marty kicks Griff between the legs and pushes him against his gang. Marty runs out the door, and Griff and his gang run after him.Outside, Biff is waxing Griff's car. Marty passes him and sees two kids with what he thinks are scooters. When he grabs one of the "scooters", he's surprised to find it is actually a Mattel "hoverboard." As in Back to the Future, he rips off the handle for the board, giving the girl the handle. Griff and his gang chase after Marty in Griff's car. Marty hangs onto the back of a passing Jeep. Biff observes the chase, and reminded of his encounter with the manure truck accident in 1955, quips, "There's something very familiar about all of this." Marty grabs onto a rope from the Jeep's back like a water surfer would be attached to a boat. When Griff swings at him, Marty swerves over the water, and the board stops. The gang tells Marty that hoverboards don't work over water "unless you've got power." Griff gets out his "Pit Bull", a jet-powered hoverboard, ready to hit Marty with his bat. The gang hooks up to the back of the Pit Bull, and all four of them fly across the water towards Marty. At the last second, Griff swings, but Marty jumps down into the water, and Griff misses. The gang fly out of control and smash through the glass windows of the courthouse.Marty climbs out of the water in time to see the gang being arrested, then flees through a pedestrian tunnel and exits out the other side. His coat suddenly announces a "drying mode", and it blow-dries itself and his hair. Marty tries to give the girl back her hoverboard, but she declines, as she now has one of the gang's Pit Bulls. A man asks for a donation to save the clock tower. An electronic billboard flashes that the Cubs win the World Series, sweeping Miami. Marty is incredulous about Miami. The man then tells Marty he wishes he could go back to the beginning of the season and put some money on the Cubs. This gives Marty an idea.Marty goes back to the antique shop and buys the sports almanac. He goes outside, looking inside the almanac, and says he can't lose. Doc arrives and tells Marty to wait. Biff comes around the corner and sees the flying DeLorean. He remarks that he hasn't seen one of those in 30 years. Marty Jr. comes out and bumps into Biff. Biff looks back and forth at Marty and Marty Jr., confused. A car almost hits Marty Jr. Doc looks at the courthouse and asks Marty what happened. Marty says, "My kid showed up and all hell broke loose". Doc sits down and says he was afraid of this. He says that after he zapped Jennifer with the sleep inducer, there wasn't enough power to knock his son out for a full hour.Biff sees Doc and hides. Marty tells Doc that the newspaper is changing. As they watch, the ripple effect occurs and the headline changes from 'YOUTH JAILED; Martin McFly, Jr. Arrested for Theft' to say 'GANG JAILED; HOVERBOARD RAMPAGE DESTROYS COURTHOUSE; GANG LEADER: 'I WAS FRAMED'. They look over and as he's being led to a police car in handcuffs, Griff shouts "I was framed!" to a USA Today camera probe, taking the same picture appearing on the paper. Doc tells Marty that his son won't go to jail; future history has been changed. He tells Marty that they succeeded, and can get Jennifer and go home. Marty accidentally drops the almanac and Doc picks it up. Doc tells Marty that he didn't invent the time machine for financial gain. Doc starts to put the almanac in the trash, but sees the police; they hide around the corner. Two cops (Mary Ellen Trainor and Stephanie Williams) have found Jennifer, and ID her with a handheld device: "McFly, Jennifer Jane Parker, 3793 Oakhurst Street, Hilldale, age 47." They are surprised she looks so young.Doc tells Marty that because the thumbprint never changes over the years, they assume she's the Jennifer of the future. Marty tells Doc that they have to stop them. Doc asks him, "What will we say, that we're time travelers? They'll have us committed." One of the cops says she's clean (i.e. no outstanding warrants), so they can take her home to Hilldale. Doc tells Marty that the cops are taking Jennifer to Marty's future home. He says they can arrive there shortly after the cops do and take her back to 1985. Marty is excited about seeing his future home and himself as an old man. Doc says no, then panics. He says, "Jennifer could conceivably see her future self. The consequences could be disastrous. There are two possibilities: 1. Face-to-face with her future self, she simply passes out. 2. The encounter creates a paradox, which starts a chain reaction and unravels the very fabric of the space-time continuum and destroy the entire universe." The police car flies by, and Doc and Marty hide against the wall. Doc hopes that they can find Jennifer before she finds herself. Looking at the digital sign, Doc says the skyway is jammed, and will take forever to get there. Doc tells Marty he didn't invent the time machine to win at gambling; he invented it to travel through time. He throws the almanac in a trash can, and they leave. Unknown to either Doc or Marty, Biff is hiding past a screen door, comes out, and retrieves the almanac, slyly realizing that Doc invented a time machine.The police car arrives in Hilldale at night, and land at the McFly (2015) house. One cop says that Hilldale is "nothing but a breeding place for tranks, lobos, and zipheads." The other one agrees, saying that they should tear it down. The cops take Jennifer to the house, and use her thumbprint to open the front door. When she wakes, they tell her she got a little "tranked", but can walk. They tell her it's dangerous without the lights on. She asks, "Lights on?" The lights come on, and they sit her down on the couch. One of the cops tells her to be careful in the future. Jennifer asks, "The future?" The cops leave. Jennifer looks at the window in front of her, but sees a giant video screen, broadcasting the 24 hr/day scenery channel. She says to herself that she's in the future. Her daughter walks around upstairs, but they don't see each other.Jennifer sees framed wedding photos of her and Marty, and picks one up. She's incredulous (and angry) that she gets married in a "Chapel O'Love" (and in the photo, we see that Marty is wearing a tux-patterned shirt, and Jennifer wears a very short skirt). When the doorbell rings, Jennifer's daughter (also Michael J. Fox), identified as Marlene when her grandparents George and Lorraine come in, asks, "Mom is that you?" Jennifer drops the photo and tries the front door, but there's no doorknob. The doorbell rings and Jennifer hides in the closet under the stairs. Jennifer looks through the slats of the closet door, but can't see her daughter as she opens the front door. Lorraine (Lea Thompson) and George (Jeffrey Weissman) come in. Marlene asks what happened to her grandpa's back. Lorraine says he threw his back out again on the golf course; George floats in upside down in a strange traction device. Lorraine asks Marlene if her folks are home yet. Lorraine is holding a small pizza in a sandwich bag, saying she bought pizza for everyone.Doc, our Marty, and Einstein are flying in the DeLorean, stuck in traffic. Doc says that old Jennifer (Jennifer 2015) usually gets home around this time, and he hopes they're not too late. Doc grabs his goggles worriedly. Marty asks him what's the matter. Doc says he thought he saw a taxi in his rear display that he thought was following them.Inside the McFly house, Lorraine is changing channels on the screen scene, saying she can't believe the window is still broken. Marlene says that when the repairman called her dad "chicken", he threw him out of the house, and now can't get anybody to fix it. Lorraine lifts it up, revealing the window. She tells Marlene that her father's biggest problem is that he loses all self-control when somebody calls him chicken. Lorraine and George say together, "Mom, I can't let them think I'm chicken." Lorraine continues to explain how in 1985, Marty Sr. got into a car accident where he got into a collision with a Rolls-Royce when someone challenged him to a drag race to prove he wasn't "chicken".The DeLorean lands outside the McFly house at night. Doc gets out, taking Einstein with him to find Jennifer. Doc tells Marty to stay there and change clothes. Marty protests, but Doc says they can't risk him running into his older self. Doc runs away with Einstein. Marty is pleasantly surprised that he will live in Hilldale. The taxi that was following the DeLorean in traffic arrives, landing down the street. After Biff pays with his thumbprint, he sneaks and hides by a waste recycling station.Lorraine continues her narrative to Marlene, saying that the accident Marty Sr. got into caused a chain reaction that has ruined his life. Had he not participated in that race, the driver of the Rolls Royce wouldn't have pressed charges and Marty wouldn't have broken his hand, he wouldn't have given up on his music career, and he wouldn't have spent the last few decades feeling sorry for himself. At that point, Jennifer hears the door open and hides in the den closet when Marty Sr. (Michael J. Fox with his hair dyed gray) comes in. She watches as Marty Jr. turns on the TV and watches several channels at the same time.Outside, our Marty is fascinated by a robotic dog walker and carelessly leaves the DeLorean's door open when he follows the dog. Biff gets in and then flies away.Lorraine puts a tiny Pizza Hut pizza in a Black and Decker Hydrator, which is completed 3 seconds, restored to full size and cooked. Lorraine is worried about Jennifer. Marty Sr. doesn't know where Jennifer is. He says she's probably in one of her mood swings. The phone rings, and Marty Sr. takes it on the large video phone in the den. It's his coworker, Douglas Needles (Flea), who wants Marty Sr. to join him in an illegal business venture. Marty Sr. balks until Needles calls him chicken. Marty Sr. says he'll do it, and scans his card, and then Needles hangs up. Marty Sr.'s boss, Ito Fujitsu (Jim Ishida), immediately comes on the phone, telling Marty Sr. that he was monitoring the card scan. He promptly fires Marty Sr. and sends out a fax saying "YOU'RE FIRED!!!" to all the fax machines in the house. Jennifer takes one of the faxes.At that point, Doc knocks on the window and tells Jennifer to go out the front door and meet him there. She says the door won't open, and he tells her to press her thumb to the plate. She tries to sneak out, but Marty Sr. is playing the guitar in the living room. Lorraine talks with him and they both leave the living room. Jennifer tries to leave, but Jennifer (2015) (Elisabeth Shue) opens the door and Jennifer hides behind the wall. When Jennifer (2015) comes in they both faint, shocked at seeing each other. Doc catches the young Jennifer.Old Biff returns in the DeLorean. When he gets out of the car, he pulls out his cane too quickly, breaking off the top of the cane in the car as he leaves. He also clutches his chest. (A deleted scene then shows him collapsing behind another car and fading out of existence). Doc calls Marty over, telling him that she fainted when she saw her old self, but she'll be fine. As they carry Jennifer back to the DeLorean, Doc tells Marty that when they get back he's going to destroy the time machine, saying that any alteration of the time continuum is too dangerous. They put her in the DeLorean. Doc tells Marty he wants to go to the Old West but it's too dangerous. He puts some garbage in Mr. Fusion & they take off.Doc, Marty, Jennifer, and Einstein arrive back in 1985, narrowly missing a jet as they appear. Doc and Marty put Jennifer in the swing on the porch of her house. Doc tells Marty to come back later in his truck and wake her up, and try to convince her it was a dream. Doc says she will probably sleep for a couple of hours. The first indication that something isn't right when Marty remarks that he doesn't remember security bars on the windows on Jennifer's house, or that the vehicle parked out front is an abandoned wreck. Doc drives to Marty's house. Due to the darkness, they fail to notice that the Lyon Estates statues have been defaced with graffiti, or a pack of stray dogs roaming the streets. Doc leaves. Marty can't open the gate to his back yard because it's locked with a padlock, so he jumps the fence. He opens the window to his bedroom and falls onto a bed in the room. To his shock, a black girl wakes up and screams "Rape!" Her father runs in and chases Marty out of the house with a baseball bat. As Marty runs, the man yells after him that they refuse to be terrorized into selling their house to the real estate company.Marty runs down the dark street, which is lined with wrecked and abandoned cars, including an abandoned police car. Gunshots are heard in the distance and a girl is heard screaming. Marty then comes upon the chalk outlines of two recent drive-by shooting victims. As Marty crosses another street, three police cars race by, sirens wailing. Marty is shocked, and figures he's in the wrong year. He finds a newspaper on the porch of a house that reads October 26, 1985, meaning he is in the right year, but in the wrong timeline.Suddenly, a shotgun is trained at Marty's head. It's Strickland (James Tolkan), who doesn't recognize Marty and thinks he is the gangbanger who has been swiping newspapers from his porch. Marty asks him why he doesn't recognize him from school, and Strickland reveals that the school was burned down by vandals six years ago. He prepares to shoot Marty's testicles off, but Marty is saved from such a potential ending when a car comes around the corner and some gangsters who recognize Strickland open fire with submachine guns, raking his house with bullets. Strickland dives into the house while Marty ducks down. As soon as the gangsters are gone, Marty stands back up, but Strickland suddenly rushes out of the house, and fires two blasts at the fleeing car, shouting "EAT LEAD, SLACKERS!"As Marty finds himself in the middle of "Hell" Valley, he bumps into Red (George 'Buck' Flower), the town bum, telling him "Watch where you're going, crazy drunk pedestrian!" Marty turns around and sees a huge casino called Biff Tannen's Pleasure Paradise anchoring the town square where the courthouse should be. There is a biker gang circling the square. A tank passes by in the street, giving the feel of a war zone. There is a toxic waste reclamation plant across the street. In the lobby of the casino, a video in the museum narrates Biff's life and success. It invites the visitor to learn the amazing history of the Tannen family, starting with Biff's great-grandfather Buford "Mad Dog" Tannen, the fastest gun in the west. You can see Biff's humble beginnings, and learn how Biff became a millionaire overnight from a large bet he made at a horse race on his 21st birthday, which led to a long winning streak that left newspapers dubbing him "The luckiest man on Earth." He subsequently parlayed his fortune to found Biffco, which runs a realty company and several nuclear powerplants. In 1979, Biff successfully lobbied to legalize gambling and converted the Hill Valley courthouse into a gaudy casino hotel. The exhibit's narrator continues to talk about Biff's life, including the women he dated (Marilyn Monroe and Jayne Mansfield) and finally his "high school sweetheart", Lorraine Baines McFly, Marty's mother. Marty screams in shock, just as Biff's goons, his old friends from high school, Match, Skinhead and 3D appear and knock Marty out.Marty wakes up in the dark and sees his mother (Lea Thompson), asking if that's her. She tells him to relax, that he's been asleep for almost 2 hours. He thinks it was a nightmare. She tells him that he's safe and sound on the 27th floor and turns on the lights. He bolts up and is shocked to see that Lorraine is an alcoholic with breast implants. She tells Marty to wait for his father. Marty asks, "Father?"Biff bursts in and angrily demands to know why Marty is not in Switzerland (implying that in this alternate reality, Marty and his siblings were shipped away to overseas boarding schools). Biff warns Lorraine that Marty is a butthead just like his father. Lorraine defends George, telling Biff that he's not even half the man he was. Biff pushes her down. Marty rushes at Biff, but Biff's men grab Marty. Biff punches Marty in the stomach. Lorraine snaps and tells Biff she's leaving. Biff asks her who will pay for her clothes, jewelry, liquor, and cosmetic surgery. Lorraine argues back that he's the one who wanted "these things", cupping her breasts. He scares her into staying by threatening to cut Lorraine off from his money, cancel Linda's credit cards, revoke Dave's probation, and put Marty and them all in jail, just like her brother Joey (perhaps the one thing in this alternate timeline that is not different from the original timeline). Biff leaves, warning her that he'll be back in an hour but Marty better not be. Lorraine tells Marty that Biff was right and she was wrong, and then pours herself a drink. Marty is shocked, wondering how she could leave George for Biff. She decides that Biff's gang must have hit Marty too hard this time, implying that in this alternate reality, Biff has a habit of hitting Marty over the head as punishment very frequently. Marty asks where his father George is. Lorraine reveals that he's where he's been for the past 12 years, at Oak Park Cemetery.Marty goes to the cemetery, and finds his father's tombstone. It shows that he died on March 15, 1973. Marty is stunned and horribly distressed and Doc steps out of the shadows, saying it's all true. Doc admits he knew Marty would come here when Marty learned about his father.Doc and Marty go to Doc's lab. Doc shows Marty newspapers from the library, which was closed down. Marty tears out the page of the newspaper that reports his father was shot dead in an alleyway while on his way to get an award. Doc explains that something caused a temporal distortion; somewhere in the past, the timeline skewed off into an alternate reality. On a chalkboard, he draws the normal timeline and the alternate timeline (1985A), which is normal for everyone else. Doc shows Marty the bag and receipt for the Gray's Sports Almanac, and Biff's fist-shaped cane top that he found on the floor of the DeLorean. It means that Biff stole the time machine and gave the almanac to himself in the past. He then shows Marty a newspaper article about the horse race Biff won a big bet on in 1958. On the front page is a photo of Biff holding a large fake cutout of a check while being interviewed by reporters. Marty uses a magnifying glass to study the photo more closely and sees the almanac is stuffed into Biff's right front pocket. Doc says this is how time travel can be misused.Marty realizes that it's his fault, and they have to go to the future to stop Biff from stealing the time machine. Doc tells him that this will not work because they would only go to this alternate future - where Biff is corrupt and powerful, married to Lorraine, and where a newspaper article shows that Doc has been committed to an insane asylum as part of one of Biff's smear campaigns. He tells Marty that they have to go the past and get the almanac, and they have to find out how and when Biff got the almanac. Marty says he will ask him.Biff is in a jacuzzi with two topless women, watching "A Fistful of Dollars" on TV (the importance of this movie will become apparent in Back to the Future Part III.) Marty comes in and turns off the TV with the remote, and confronts Biff about the Grays Sports Almanac. Biff sends the women out. He asks Marty what else he knows about the book. Marty demands to know how, where, and when he got the book. Biff tells (orders) him to sit down. He says, "November 12, 1955", then opens a safe. Marty says that was the date of the lightning storm. Biff says that it was a Saturday, and he crashed his car drag racing. Marty, however, knows that Biff crashed into a manure truck, that his father told him about it before he died. Biff continues, saying that a "crazy old codger" (his old self) gave him the almanac, asking him how would he like to be rich, and that he was a distant relative. Biff claims he didn't see the resemblance. Biff reveals that his old self told him he was going to be rich, and when Biff asked if there was a catch about the almanac, the old self told him, "No catch; just keep it a secret." Biff says he never saw him again.While Biff turns his back to put the almanac back in the safe, Marty takes one of the matchbooks from an ashtray. Biff then remembers something else: old Biff warned him that "Someday a crazy wild-eyed scientist or a kid will show up. If that ever happens[, kill him]...." Biff pulls out a snub nose revolver, saying he didn't think it would be Marty, and prepares to shoot him. Marty throws the ashtray at Biff, but he ducks and the ashtray sticks into Biff's chair.Marty runs upstairs, and Biff shoots at him several times, but misses. Biff's goons chase after Marty, but he jumps the other flight of stairs and goes back upstairs to the roof instead, while they go downstairs. Biff catches up and sees the door to the roof swinging, and follows Marty. He tells Marty to jump, that suicide would be nice and neat.Marty warns the police will trace the bullet, but Biff brags that he owns the police; his influence is how he was able to get away with murdering George. Marty jumps over the ledge and Biff can't believe it. He calls Marty an idiot, and then looks over the ledge. Marty comes up on the DeLorean, and the door knocks Biff out. Doc and Marty fly away. Doc sets the time machine for November 12, 1955. The display malfunctions and shuts off; Doc hits it and it returns. Doc tells Marty it's unbelievable that old Biff chose that date, that it must have cosmic significance.Doc and Marty return to the morning of November 12, 1955 and hide the DeLorean behind the Lyon Estates billboard, much like Marty did when he first arrived. Doc tells Marty he will repair the short in the time circuit. He tells Marty to get the book back, but warns him to be careful not to run into his other self. He gives Marty some 1955 money from an emergency money suitcase containing US money from different periods, and tells him to buy some inconspicuous clothes.The next morning, Marty has a pair of binoculars and is dressed like a 50s greaser in a leather jacket and wearing a hat, like a spy. He is communicating with Doc via two-way radio and outside the house of Gertrude Tannen, the only Tannen listed in the phone directory. Marty is skeptical that Biff lives here...just as Biff comes out of the house, looking exasperated with his grandmother. He follows Biff to a mechanic's shop in the middle of town. Terry, the mechanic who repaired Biff's car after the manure truck incident, drops it off, and Biff is outraged to find that the repair bill is $300, including an $80 fee from Jones to remove the manure. We see Old Biff is hiding behind a tree, chuckling as he recalls the incident. Biff and the mechanic go into the shop to argue about getting a refund for the fee Jones is charging Biff, during which Marty climbs into the back of Biff's car.Minutes later, Biff and the mechanic return, still arguing. Biff tosses a few oil cans in the back of the car, much to Marty's discomfort. The argument ends as the mechanic drives away in a hurry, fed up with Biff. Just then, Biff is distracted when he sees Lorraine and one of her friends rush out of a dress shop a few doors down the street, excitedly admiring the dress Lorraine has just purchased for the dance. His mood brightens, and he goes over to harass her. He wants her to go with him to the dance, but she counters she's going with "Calvin Klein" (Marty's alter ego). Biff is infuriated, he's not happy that Lorraine doesn't want him, and gets more forceful with her. Lorraine gets more annoyed, finally telling Biff she won't go with him to the dance even if he had a million dollars. To express her opinion, she kicks him in the knee, then clocks him over the head with her dress box and runs off even as Biff taunts her that she is going to be his wife one day. Biff goes back to his car and finds old Biff sitting in the driver's seat. Biff, exasperated, tells old Biff to leave, but old Biff starts the car, shocking Biff. Old Biff tells Biff to get in, telling him it's his lucky day.The scene cuts to Old Biff driving Biff rather recklessly back to Biff's house. As they park in the garage, Biff demands to know how Old Biff knows where he lives. Old Biff gives Biff the almanac, telling him it will make him rich. Old Biff explains that it lists sports results from 1950 to 2000. Biff tosses it back and tells old Biff to "Make like a tree and get out of here!" Old Biff slaps him in the back of the head & corrects him, "It's leave, you idiot!" Biff demands proof that the almanac is what old Biff makes it out to be. Old Biff turns on the radio to a football game, and surprises Biff when he announces that UCLA, trailing 17-16 with 20 seconds to go on the clock, will win 19-17. The radio announcer reports that UCLA wins 19-17.Old Biff tells Biff to always bet on the winner, and gives Biff back the almanac. Biff tosses it in the back of the car, but old Biff grabs it before Marty can and stuffs it into the back pocket of Biff's pants, gravely reminding him to never let the book out of his sight. Old Biff and Biff close the the garage door and walk away as Old Biff warns Biff about Marty or Doc coming to confront him about the almanac. Marty gets out of the car and tries to follow them, but the garage door is locked with a padlock. He calls Doc on his walkie-talkie, telling him Biff and old Biff left with with the book; Doc radios that he'll find a way to get there without a car.That night, Biff comes back to the garage while having to deal with his domineering grandmother yelling at him. He opens the garage and gets into his car, preparing to leave for the dance. Marty gets in the back of the car without Biff noticing. Doc passes the car just after they leave and sees the open garage door, wondering where Marty is.As he drives into town, Biff listens to "Papa Loves Mambo" by Perry Como on the radio. Marty calls Doc. Doc sees the tarp that covers the DeLorean. Marty tells Doc they are going to the dance. Doc tells Marty that they need a new plan; it's too dangerous. Marty tells Doc that he's in Biff's car. Doc warns Marty that he must not let his other self see him because of the consequences. Just then, the 1955 Doc appears and asks 1985 Doc to get a wrench from the toolbox. Doc asks him if he's doing a weather experiment, surprising him. Doc says that he has experience in this. Doc (1955) suggests that maybe they'll bump into each other in the future. As 1985 Doc rides away on his bicycle, 1955 Doc looks at the back of Doc's head, and does a double take.Biff (and Marty) arrive at the dance. Biff takes the almanac with him; Marty follows Biff inside. The band is playing and students are dancing. Marty sees through the binoculars that George is dancing alone. He also sees Biff's gang Match, Skinhead and 3D spiking the punch with liquor, and sees the almanac in Biff's back pants pocket. They quickly have to retreat when Strickland notices them.Biff and his gang leave; Marty follows them. Biff tells his gang that he's still looking for Calvin Klein because he caused $300 damage to his car. The gang goes back inside, but Biff stays outside, and reads the almanac after tossing the liquor bottle away. Marty sees his counterpart drive up with Lorraine. He sees the almanac in Biff's back pocket, and jumps down. Biff looks around, hearing a noise, but doesn't see anyone.Just as Marty is about to grab the almanac, Strickland surprises Biff, who turns around. Strickland detects a whiff of alcohol on Biff's mouth. He confiscates the almanac, calling Biff a slacker, and walks away; Marty secretly follows him. Strickland goes to his office and drinks coffee, spiking it with liquor. Marty enters quietly, but hides under the desk when the door noisily swings shut. When Marty reaches for the almanac, Strickland backs up in his chair against Marty's hand; Marty stifles a scream. Strickland leaves and tosses the almanac in the trash can. Marty retrieves the almanac, but finds out it's a girlie magazine; only the cover was from the almanac.He calls Doc and tells him that Biff must still have the almanac. Through the window, we can see George's struggle with Biff. Marty hears the ruckus and runs outside. He arrives just as George punches Biff, and sees his counterpart and the crowd. Marty's counterpart looks at the photo (as before) and runs away. Marty comes in and tells the crowd gathering around Biff to back off, and then tells them he knows CPR. A guy asks, "What's CPR?" Biff wakes up, and recognizes Marty as "Calvin Klein," but Marty punches him and knocks him back out, then takes the almanac. The bystander thinks that Marty just pickpocketed Biff's wallet.Biff's gang chases Marty. Doc tries to take off and bumps into the billboard, catching the streamer attached to it. While he makes a shaky takeoff, the time machine's display changes to January 1, 1885. At the dance, Marty sees George and Lorraine, and his 1985 counterpart. George and Lorraine kiss. Biff's gang enters, and Marty hides under a table. The gang sees Marty's counterpart on stage about to play "Johnny B. Goode", and prepare to nab him. Marty calls Doc, who tells him his counterpart will miss the 10:04 PM lightning bolt at the clock tower. Doc tells Marty he has to help his counterpart at all costs, or there will be a time paradox.Outside, Biff comes around, hearing Marty's counterpart playing "Johnny B. Goode," and asks the bystanders where Marty has gone. The guy who saw Marty take the almanac tells Biff where Marty went, and Biff heads into the building.Marty sees Biff's gang backstage. He goes backstage, climbs up into the overhead rafters and pulls the ropes, releasing the stage weights (sandbags) on the gang just as Marty's counterpart finishes playing the high note. Marty swings down and drops the bags again, knocking the gang out.Marty calls Doc, who tells him to meet on the roof of the gym in one minute. Marty leaves, and through the door window sees his counterpart talking to Lorraine and George. Biff suddenly appears, nose bloodied, and not fooled at all by Marty's "disguise". Marty tries to walk away from a potential fight, only for Biff to call him chicken. Before Marty can fight Biff, his counterpart slams the door open, knocking him down. After counterpart Marty leaves, Biff sees the almanac in Marty's hand. Furious, he kicks Marty for taking the almanac, damaging his car, and humiliating him, then marches to his car and drives away. Marty makes it to the roof of the gym and tells Doc that Biff has stolen the book. They follow Biff, flying over him in the DeLorean. They sneak up quietly behind Biff's car. Marty gets on the hoverboard, hiding behind the back of Biff's car, and Doc flies away. Biff turns, thinking he heard a noise, but doesn't see Marty.Marty pulls up to the passenger side of the car and sees the almanac. Biff, listening to sports on the radio, reaches for the almanac to check the scores just announced, and then puts it back on the seat, memorizing them for later use. Marty opens the door, but Biff sees him. A struggle ensues as Biff enters a tunnel, trying to smash Marty against the wall, but Marty swings aside. When Marty tries to sneak in, Biff punches him.They're now on the wrong side of the road, but Biff swings back and dodges a passing truck. Marty grabs the almanac and jumps down, and Biff turns around. Biff revs the engine and Marty tries to fly away on the hoverboard. As Biff races towards Marty, it's doubtful that Marty will reach the end of the tunnel before Biff reaches him. Marty reaches the end of the tunnel in time and grabs a streamer that Doc has lowered from the DeLorean, lifting him clear of the tunnel. Biff, racing at full speed, looks up, shocked. Just as his eyes return to the road, he sees a manure truck stopped in the road. Biff slams on the brakes, but it's too late, and he plows into the back of the truck, which dumps its entire load into the car again. He screams, "Manure! I hate manure!"Doc and Marty return to the billboard, just as a thunderstorm rolls in. Doc lowers Marty to the ground on his hoverboard. A storm is creating turbulence, so Doc has to come around from another direction to land. Doc asks Marty about the almanac, and tells him to burn it. Marty puts it into a bucket and burns it with matches from Biff's casino.When he does so, the words on the change from "(Biff's) Pleasure Paradise" to "Auto Detailing". The newspaper headline changes from "GEORGE MCFLY MURDERED" to "GEORGE MCFLY HONORED". Marty calls Doc, telling him that the newspaper changed and his father is still alive. Doc sees another newspaper headline change from "EMMETT BROWN COMMITTED" to "EMMETT BROWN COMMENDED", and says, "Mission accomplished." Marty asks Doc if everything is back to normal, if Jennifer and Einstein are okay. Doc says yes, it's the ripple effect, and that they can go back to their own future. A lightning bolt strikes a tree across the street from Marty, and he ducks. Doc quips he (Doc) almost bought the farm. Seconds later, another lightning bolt strikes the DeLorean, and it vanishes, leaving behind two fiery contrails. Marty tries unsuccessfully to call Doc on the radio, but it is useless. The streamer drops to the ground, the end smoking.Moments later, as the rain begins pouring down, a car pulls up. A mysterious-looking man gets out of the car and informs Marty that he is from Western Union, and they have been holding a certain letter for the last 70 years, with instructions to deliver it to Marty at this exact place and time. The man lost a bet whether or not Marty would be there. Marty signs for the folder; opening it to find a letter from Doc. He reads the letter aloud as the man listens. Doc says that he's alive and well. Marty reads that Doc is alive in the year 1885, in the Old West. The man asks Marty if he needs any help. Marty replies that there's only one man who can help him, and runs away.Doc's counterpart has just finished helping Marty's counterpart return to 1985, and is running down the street laughing. Marty runs to him and grabs him from behind. Doc is shocked, saying that he just sent Marty back to the future. Marty says that he's back from the future, and Doc faints. Marty tries to revive Doc.The movie ends with a title card reading "TO BE CONCLUDED..." and previews of Back to the Future Part III.
question: Who does Marty switch places with in the beginning?
answer: Marty Sr