Underworld is a 2003 action horror film directed by Len Wiseman about the secret history of Vampires and Lycans an abbreviated form of lycanthrope. It is the first chronologically, the second installment in the Underworld series. The main plot revolves around Selene Kate Beckinsale, a vampire Death Dealer hunting Lycans. She finds herself attracted to a human, Michael Corvin Scott Speedman, who is being targeted by the Lycans. After Michael is bitten by a Lycan, Selene must decide whether to do her duty and kill him or go against her clan and save him.
For generations, a secret war has been waged between vampires and Lycans, an ancient species of werewolf. Selene, a Death Dealer, a vampire specialized in assassinating Lycans, tracks two Lycans. Selenes motivation goes beyond duty she also wants revenge because, 600 years ago when she was a child, Lycans slaughtered her family. The vampires believe they defeated the werewolves many centuries ago and killed their leader, Lucian, and that they must kill the surviving Lycans. Selene locates the Lycans den and learns they have developed a new kind of bullet capable of killing the vampires.Later, Selene arrives at the mansion of her vampire coven and, recounting these events, urges an attack on the Lycans but the vampire regent, Kraven, dismisses her proposal. Selene determines that the pair of Lycans may have been following a human, Michael Corvin, and continues her investigation. In a Lycan lair, a scientist named Singe tests blood from kidnapped descendants of the ancient Corvinus family, trying to find a pure source of the ancient and powerful Corvinus bloodline. Soon after Selene finds Michael, the pair are attacked by Lycans, including their leader, who is revealed to be Lucian. Lucian bites Michael, but Selene helps Michael escape and the two become attracted to each other. ........
Source: Wikipedia