context: It is a Friday night in April 1968 in Chicago. Johnny Ross works with his brother Pete; both are involved with organized crime, and the mob is after Johnny Ross because he siphoned off $2 million of their money. Johnny escapes a mass of gunmen outside his office, then greets Pete in the garage of their office building. The two exchange brotherly greetings and go on their way - Johnny drives past yet another attempt on his life while Pete telephones his higher-up and tells them that Johnny escaped.Saturday afternoon in San Francisco. A man goes to a hotel and asks the desk clerk for a message for "Johnny Ross", and seems surprised that no message is there. The man takes a cab and has the driver stop by a phone booth, where the man makes a pair of calls, one of them long-distance. At that point, Sgt. Don Delgetti of the SFPD awakens his partner, Detective Lt. Frank Bullitt, at his apartment. Bullitt has been trying to get some sleep after a case that stretched to 5 AM that morning and grumpily chats with his partner.After showering and getting dressed, Frank Bullitt is driven by Delgetti and another policeman, Sgt. Carl Stanton, to the plush mansion of politician Walter Chalmers, who is entertaining a vast pool of guests at a function. Chalmers tells Frank of a star witness who will testify against the mob - Johnny Ross - and who needs protection through his appearance to testify on Monday morning. Chalmers clearly hopes to use Ross as well as Bullitt to the benefit of his political career, and leaves Frank and his two partners to guard Ross at the Hotel Daniels, a flophouse near an passing highway.Frank, Delgetti, and Stanton meet the man who had inquired about a Johnny Ross letter, and the man is puzzled about Chalmers putting him up in such a cheap hotel. After phoning his boss, Captain Samuel Bennett, Frank arranges three shifts to guard Ross, with Delgetti going first, then Stanton, then Bullitt.Around 1am the following morning Stanton gets a call from the Hotel Daniels front desk claiming that Chalmers and a friend want to see them. Stanton has the two men wait, then calls Frank, who realizes something is wrong and rushes to the Hotel Daniels. Stanton then notices the door to their room is unlocked, just as the two men - a 5' 10" white-haired shotgun killer and his back-up man - kick the door open and shoot both he and Ross.Delgetti and ambulances arrive before Frank does, and Frank accompanies Stanton in the ambulance ride to the hospital, where the injured officer describes the gunman, identifies the gun brand (a Winchester pump-action shotgun), and relates that Ross unlocked the door, to the puzzlement of Frank.Captain Bennett arrives at the hospital after getting a report on the hotel from the SFPD crime lab, and after getting what he can from Frank warns him that Chalmers is livid upon learning of this fiasco and will try to lay the blame on the department in general and Bullitt in particular. For his part, Bullitt is ready when Chalmers arrives and questions him; Chalmers demands to know how Bullitt fouled up the protection detail and Frank pointedly asks Chalmers about Chalmers' deal with Ross, but the oily politician vows to ruin Frank's career if Ross dies - even to the point of requesting a different doctor be assigned to Ross.A white-haired man - the shotgun killer - appears at the hospital and asks a doctor about a friend of his with a gunshot wound; the doctor tells him that it might be the man on the second floor (Ross), then phones Bullitt. Frank has a policeman guard Ross' room, and when a nurse catches the shotgun killer untaping an icepick from his leg, Frank chases him through the hospital. Bullitt nearly corners the man in the physical therapy wing in the basement, but the killer eludes him and escapes.More bad news arrives when Ross suddenly goes into respiratory failure and dies. Frank tells the doctor not to confirm Ross' death, as Chalmers will ruin them both. Bullitt also believes that the killers, upon knowing they've succeeded, will disappear; the doctor agrees to misplace Ross' files and Frank has Delgetti take Ross' body under the name John Doe to the coroner's office.While Frank goes home to shower and get some rest, Chalmers, accompanied by a posse of assistants and police Captain Baker, arrives at the hospital and immediately demands to know Ross' location. The supervising nurse tells Chalmers that Ross' file has been misplaced. He telephones Bullitt and gets the runaround, and tells Baker to punish Bullitt for the mishap.Frank and Delgetti, meanwhile, question the Hotel Daniels desk clerk -- he'd been hit & knocked unconscious by the killers. They get a description of the cab Ross arrived in as well as a description of the driver; Frank deduces who drove Ross and rides with the cabbie in question and learns about Ross' phone calls -- the cabbie has a sharp recollection of Ross' stops during the ride & is able to point out that Ross had made a long distance phone call at a phone booth. Frank telephones Eddy, an informant, and they arrange a meeting near Enrico's restaurant, where Eddy tells Frank about the mob's pursuit of Ross and what they're after him for.Chalmers, meanwhile, intercepts Captain Bennett while he and his family are going to mass and serves him with a legal writ, duly witnessed by two of Chalmers' aides-de-camp, requiring Bennett to turn in Ross by Monday morning.After being dropped off at his own car at the cabbie's garage - a Ford Mustang - Frank notices that a black Dodge Charger has been following him around the city. He drives around some of the hilly side streets and eludes his pursuers enough to become the pursuer himself. The two mob assassins, realizing they've been outmaneuvered, make a break and a mad high-speed pursuit ensues through the hills of the city and eventually spilling onto a two-lane freeway. The shotgun man finally opens fire on Frank but Frank rams his Mustang into the Charger as they approach a gas station/repair shop; the Charger flies off the road, plows through the gas station, and explodes as pumps are sheared off, killing both gunmen.Frank and Delgetti are now angrily questioned by Bennett and Baker and Frank reveals Ross' death, and that a check of phone records shows that Ross called a woman, Dorothy Simmons, staying in a San Mateo hotel hours before his death. Bennett holds the legal writ until Monday morning, giving Frank one day to prove the two men killed in the gas station were Ross' killers. He is driven to the San Mateo hotel, but he finds the woman dead, and later a search of their luggage reveals that she had a man with her and that both of them had books of travelers checks worth tens of thousands of dollars; moreover, the woman is not Dorothy Simmons but Dorothy Renick, and the man she is with is her husband Albert.Delgetti calls Chicago to fax passport information to the SFPD while Frank gets a fingerprint check on Ross at the coroner's office. The fax printout comes through and Bullitt shows that Chalmers had the wrong man the whole time. Frank and Delgetti now must comb the San Francisco Airport to find the real Ross while Chalmers, determined to take in the real Ross himself, follows. Renick was originally booked on a flight to Rome, however, after he arrives at the airport, he switches to a flight to London. Frank, going on a hunch when Renick doesn't show at the Rome check-in, manages to stop the plane Ross is on before departing, and identifies Ross by his expression and actions. Ross jumps off the plane and runs across the runway, with Frank pursuing. Ross runs back into the terminal as Delgetti arrives with a security guard. Trapped between two automatic doors, Ross tries to shoot his way out, but Frank kills him. Chalmers leaves, disgusted that he's lost his star witness.Frank returns home, where his girlfriend is sleeping, and starts to wash his hands. She had earlier expressed fear that he was becoming as inhuman in his own way as the criminals he pursues - and now he wonders if she may be right.
question: Who is a defector from the Chicago organization?
answer: Johnny Ross