Selene, a vampire warrior, is entrenched in a conflict between vampires and werewolves, while falling in love with Michael, a human who is sought by werewolves for unknown reasons.
Picking up directly from the previous movie, vampire warrior Selene and the half werewolf Michael hunt for clues to reveal the history of their races and the war between them.
An origins story centered on the centuries-old feud between the race of aristocratic vampires and their onetime slaves, the Lycans.
A few years after the events of Underworld: Evolution, both the government and the general public have become aware of the existence of the Vampires and Lycans. A program to study and potentially harness their powers soon escalates into an all-out genocide and shortly after the "Purge" begins, Selene and Michael are captured by humans. Due to her enhanced vampiric traits, Selene is imprisoned in cryogenic suspension.
The remaining Vampire covens are on the verge of annihilation by the Lycans. Both species are searching for Selene: the vampires seek justice for the death of Viktor, while the Lycans, led by Marius, intend to use her to locate Eve, whose blood holds the key to building an army of vampire-werewolf hybrids.