Underworld

The movie opens with Selene, a Death Dealer, and Rigel trailing a pair of Lycans, unaware that they are in turn stalking a human - Michael Corvin. Trailing them into a subway station, the two Death Dealers are spotted and a shoot-out ensues, with Rigel being killed by the Lycans. A woman is shot in the crossfire, and Michael tries to assist her. The two sides of monsters continue their fight, and the Lycans eventually retreat.

Arriving at Ördögház, Selene confronts Kahn, the chief Death Dealer, with her findings during the battle; but the regent Kraven blows off the significance of her claims. Selene decides to further investigate the ordeal alone. Meanwhile, in the Lycan lair, a scientist named Singe unsuccessfully seeks a match for the Corvinus Strain. They decide to try again in pursuit of Michael.

Selene finds Michael and demands answers. They are attacked by Lycan hordes, including Lucian, the original Lycan leader who is thought to be dead. Michael is bitten by Lucian, who gathers a blood sample. Selene, unaware of him being bitten, aids Michael in escaping the building. Selene takes Michael to the vampire lair for safety, but he soon escapes when the other vampires figure out he's become a Lycan. Selene grows suspicious of Kraven and collects evidence to take to the library. She learns that Lucian is still alive and that he and Kraven are secret allies with each other. Selene decides to awaken Viktor, an elder.

Michael tries to seek aid from his friend at the hospital, but his tale of being bitten by a man leads to treachery on the part of his friend. He escapes again, attempting to meet with Selene and begging for answers. Selene drives out to meet Michael, where she sees that he had indeed been bitten. She explains the long history between Vampire and Lycan. Kraven runs into Viktor, who demands to know what has happened, and learns that he has been awakened a century early.

Selene takes Michael to a safehouse. Michael mentions his nightmares and Selene explains they are actually Lucian's memories. Selene explains that her hatred of Lycans stems from her belief that they killed her family. Michael is captured while another Vampire-Lycan firefight breaks out. Selene ends up the only vampire survivor and Singe the only Lycan survivor.

Kraven tries to explain what has happened to Viktor right as Selene arrives with Singe. The captive Lycan reveals that the Lycans had been experimenting to combine the bloodlines of the two species via the Corvinus Strain, something they can only do with a descendant of Alexander Corvinus himself, which is why they targeted Michael. They wished to make a Hybrid so they could end the war. He also reveals Kraven's treachery, forcing Kraven to flee. Kahn arrives at the crypt and informs Viktor that the Vampire counsel, including Amelia the 'active' elder, was attacked by the Lycans and there were no survivors. Viktor kills Singe and turns to Selene telling her all she has to do is kill Michael and she will be exonerated.

Michael wakes up strapped to a slab in Singe's lab. He is greeted by Lucian, who then extracts blood from Michael and injects it into himself. While Michael watches him, he recognizes the pendant Lucian wears, and suddenly, his nightmares make sense: he recalls the events of how Lucian's wife, Viktor's daughter Sonja, was murdered by Viktor out of fear that the infant in her womb would be a hybrid that would overthrow him. Viktor, it is revealed, started the war. Lucian explains the rest of the story to Michael.

The vampires begin their attack on the Lycans' base, and a running battle through the caverns ensues. Meanwhile, Kraven betrays Lucian, shooting him in the back. Selene finds Michael and unties him, telling him to leave despite his protests that they will kill her for releasing him. Kraven discovers them and a confrontation ensues. Out of spite, Kraven reveals that Viktor was the one who killed her family. Viktor was unable to kill Selene because she reminded him too much of his daugther Sonja. Lucian, not yet dead, appears and distracts Kraven long enough to advise Selene to bite Michael, reminding her of Singe's words. She takes his advice and bites Michael. Kraven finishes Lucian off. Selene confronts Viktor, who despite his guilt, defends all his actions.

Michael changes into his hybrid form and battles with Viktor. Selene kills Viktor by slicing his head in half. Selene picks up Sonja's pendant and gives it to Michael to keep. They walk out together, speechless and numb. Selene then narrates to the audience that she fears she will become a target following Viktor's death. Back in the crypt, Singe's blood pours across the floor until it reaches the remaining elder's sarcophagus. Marcus' eyes flutter open. First vampire blue, then hybrid black..