Underworld is a 2003 action horror film directed by Len Wiseman and written by Danny McBride, based on a story by Kevin Grevioux, Wiseman and McBride. Kevin Grevioux wrote the original screenplay. The film centers on the secret history of vampires and lycans (an abbreviated form of lycanthrope, which means werewolf). It is the first (chronologically, the second) installment in the Underworld franchise. 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. Alongside Beckinsale and Speedman, the film stars Michael Sheen, Shane Brolly, and Bill Nighy.

Plot

For generations, vampires and Lycans, an ancient species of werewolf, have secretly waged war. The vampires gain the upper hand when Lycan leader Lucian seemingly dies at the hands of vampire Kraven, who becomes the second-in-command to the vampires' leading elders. Selene, a member of an elite group of vampire assassins known as "Death Dealers", continues to pursue the extermination of the Lycans despite other vampires no longer perceiving them as a threat.