context: NOTE: Sequel to Underworld (2003).Underworld: Evolution opens with Vampire Selene (Kate Beckinsale) recapping the events in Underworld. Selene is a Hungarian Vampire who had been a Death Dealer for the Vampire clan throughtout Europe for 600 years when she was betrayed. She explains how Kraven (Shane Brolly), the ruler of the Vampire clan, formed a secret alliance with Lucian (Michael Sheen), ruler of the Lycan clan. When the Lycans found a third bloodline (human) that also descended from ancestor Alexander Corvinus, they tracked down descendent Michael Corvin (Scott Speedman) and turned him into a Lycan. After a big fight between Lycans and Vampires, Lucian was killed by Kraven. Before Michael died, however, Lucian told Selene to bite Michael: "Half Vampire, half Lycan -- they're stronger than both." Thus, Selene turned Michael into the first Hybrid. Selene then beheaded Elder Viktor, and she and Michael went into hiding.With two of the three vampire Elders destroyed (see Underworld), Selene's only hope is to awaken the last remaining Elder, Marcus (Tony Curran), who is still in hibernation, and expose the truth before Kraven can kill Marcus. Selene hides Michael in a safehouse and heads over to the Vampire mansion to plead her case. Unfortunately, Kraven has already attempted to awaken Marcus, who has morphed into some sort of bat-like creature, and Marcus has killed Kraven as well as all of the other Vampires in the mansion, including Erika (Sophie Myles) (Note: Erika's brief appearance just before her death appears to be taken from archive footage from the previous movie). By drinking Kraven's blood, Marcus learned everything that has transpired while he was in hibernation, including the making of Michael into a Hybrid. Marcus locates the safehouse in which Michael is hiding, but Michael has gone out for a bite to eat. After downing half a plate of potatoes and cabbage, he begins to retch (being half Vampire, he needs to feed on blood). Suddenly a newsflash is shown of him on the television. Several of the restaurant patrons try to hold him with their guns, but Michael escapes. Selene realizes that Michael is gone and goes after him. Michael has been shot several times and is in need of blood, so Selene makes him drink some of hers.Just then, Marcus flies in. He attempts to drink from Selene (to gain her memories and knowledge), but Michael pumps a few bullets into him. Selene and Michael steal a truck and outrun Marcus, who flies behind them. Suddenly, Selene notices the sun is about to rise. Michael helps her drive the truck into a warehouse and darkens the windows with paint. The two of them hole up there for the day. Big love scene follows as both of them give into their passion and have sex.After sunset, Selene and Michael go looking for Andreas Tannis (Steven Mackintosh), Vampire and exiled historian of Vampire history, in order to get him to identify a pendant necklace that has been in Selene's possession since childhood. Selene learns from Tannis that the pendant is actually a key to Lycan William's prison, a place that was built by Selene's father. Selene now learns the truth about the slaughter of her family: Viktor did it to keep anyone from knowing William's whereabouts. Selene is the only one left who might remember where William's prison is located, and that memory is locked in her subconscious. It is for this reason that Marcus wants her blood...so that he can find William. Viktor did not fear for William and Marcus's lives when he ordered William imprisoned for all eternity. He feared that destroying William would destroy the entire Lycan bloodline, thus leaving the Vampires without slaves.Tannis arranges a meeting between Selene and Lorenz Macaro (Derek Jacobi), the only one who may have the power to stop Marcus. Before Selene and Michael can get to Lorenz Macaro, however, Marcus gets to Tannis and learns that there were actually two keys, the one with Selene and the other sewed inside Viktor's abdomen, a key that was removed by Alexander Corvinus upon Viktor's death. Lorenz Macaro turns out to be Alexander Corvinus. Selene begs him to help her stop Marcus, but he refuses to kill his own son. Suddenly, Marcus appears.
  Michael tries to fight him, but Marcus impales Michael through the chest and takes Selene's key that Michael was holding at the time. Selene shoots Marcus, who flies off. She removes the impalement from Michael's chest, then drains her own blood over the gaping wound... to no avail. Michael is dead.Marcus runs a sword through his father and takes the key that his father took from Viktor's chest. Marcus is now in possession of both keys. As he lays dying, Alexander slits his wrist and makes Selene drink his blood in order to pass on the legacy. "What will I become?" she asks. "The future," Alexander replies. As a helicopter takes off, carrying Selene cradling Michael's body, Alexander blows himself up.Now that Marcus has both keys and the knowledge of where the door lies, he opens it and finds William waiting. Selene leads the helicopter to where she remembers a secret passage into the prison and enters, along with a few backups. Once in, they hear the roar of a werewolf and meet up with William. Selene fires at William just as Marcus appears. Selene fires at Marcus, slowing him just long enough to get through the open door and close it behind her. Unfortunately, a bit of rock prevents the door from closing all the way. William catches up with Selene again. She fires at him repeatedly and blows up the cavern in which they are located. Suddenly, all the backups killed by William begin to turn into werewolves and converge on Selene.Meanwhile, back in the helicopter, Michael lives! He leaps from the helicopter into the fracas and helps Selene battle with William. However, Marcus has managed to get the door open, and he, too, joins the melee. The
  first thing he does is to grab on to a rope hanging from the helicopter and bring it tumbling down into the cavern where it catches on a catwalk and lies there, blades still spinning. Now it's Michael against William and Selene
  against Marcus. Eventually, Michael manages to behead William, and Selene shoves Marcus into the helicopter blades, tearing him to pieces.As the sun comes up and Selene realizes that she is no longer burned by the light, thanks to Alexander Corvinus's blood, she and Michael enter each others' arms. Big kiss scene follows.[Synopsis by bj_kuehl]
question: What does Markus want?
answer: the two keys