In the Underworld, Vampires are a secret clan of modern aristocratic sophisticates whose mortal enemies are the Lycans (werewolves), a shrewd gang of street thugs who prowl the city's underbelly. No one knows the origin of their bitter blood feud, but the balance of power between them turns even bloodier when a beautiful young Vampire warrior and a newly-turned Lycan with a mysterious past fall in love.