In the year 1202 A.D. an army led by three vampire elders (Markus, Viktor, and Amelia) arrives at a Lycan ravaged village. After killing several werewolves, Viktor and Amelia capture their target: Markus's brother, William Corvinus, the first and most powerful werewolf. Despite Markus's defiance, Viktor orders that William be imprisoned in a secret location forever.
In the Present Day (just after the events of the first film), Selene takes Michael to a safe house so that she can return to the mansion to confront Kraven. She knows Kraven intends to kill Markus and plans to stop him. However, Singe's blood has already awakened Markus, turning him into a Vampire-Dominant hybrid. Markus then wipes out Kraven and his men, and destroys the mansion. He learns Selene and Michael's location from camera surveillance of various safe houses and leaves to track them down. Markus attacks Selene and Michael, who evade him and hide in a warehouse. While inside, Selene and Michael share their feelings and make love.
Lorenz Macaro, an elderly and imposing man, sends in a team of "Cleaners" to investigate the aftermath from the battle in the Lycans' lair. When Macaro examines Viktor's body he finds a metal disk attached to his ribcage which is the match to Sonja's pendant, which is in the possession of Selene and Michael. Now knowing that the pendant is of some importance to Markus, Michael and Selene set out to solve its mystery. Selene recalls that she'd seen it as a child, but doesn't know its significance. To find answers, they travel to the hideout of the exiled vampire historian, Andreas Tanis. Selene and Michael confront Tanis, who reveals that Markus, not Viktor, was the first vampire; one of the three sons of Alexander Corvinus, the first immortal. Markus was bitten by a bat and became a vampire; his twin brother, William, was bitten by a wolf and became a werewolf. The third son remained human his entire life and gave rise to a line of descendants including Michael, who became the first Lycan-Vampire Hybrid. The first werewolves created by William were entirely animal and unable to take human form again. Due to William's destructiveness, Markus approached Viktor, a warlord dying of old age, and offered to turn him and his army into immortal vampires in exchange for tracking down and stopping William, and in destroying those he had infected.
Markus intended to capture his brother and tame him, but Viktor ordered that William be locked away forever, far away from Markus. Viktor did not kill the brothers because he believed that doing so would result in the immediate extinction of all other vampires and his Lycan slaves (a deception he had been fed by Markus). Tanis also reveals that Selene's father was the architect who built William's prison and that the pendant is a key. After Lucian's escape, Viktor killed Selene's family as they knew of the prison's location, but turned Selene into a vampire. Tanis then refers Selene and Michael to Lorenz Macaro for help. Shortly after they leave, Markus arrives and questions Tanis, who lies desperately and tries to evade telling Markus of his telling Selene the family secrets. Tired of hearing Tanis's lies, Markus learns the truth by drinking his blood, leaving Tanis unconscious.
Italiano
Dopo un breve prologo in cui si scoprono le origini delle due razze, Vampiri e Lycan, e di come Viktor, Amelia e Marcus hanno catturato e imprigionato William, il gemello di Marcus e capostipite dei Lycan, si torna al presente: Kraven, coi pochi seguaci rimastigli, giunge alla tomba di Marcus per ucciderlo e prenderne il potere, ma scopre che questi è già stato risvegliato dal sangue del dott. Singe. Cosi Marcus lo uccide e parte alla ricerca di Selene. La incontra ma non riesce ad ottenere informazioni su dove sia la prigione di suo fratello William.Selene e Michael, dopo essere sfuggiti sia a Marcus che alla luce del giorno si recano alla dimora di Tanis, l'antico storico dei vampiri, che secoli prima è stato bandito ed esiliato per aver pubblicato la verità sulle scelleratezze compiute da Viktor. Tanis, dopo aver sguinzagliato contro i due fuggitivi i suoi Mannari da guardia, donatigli da Lucian anni prima, fissa per loro un incontro con qualcuno che avrebbe fornito loro delle informazioni. Poco dopo la loro partenza Marcus giunge da Tanis e lo uccide dopo aver saputo dove si trovano le due chiavi che aprono la prigione di suo fratello: una è nascosta all'interno del corpo di Viktor, l'altra è composta dall'amuleto che Lucian portava al collo e che ora è nelle mani di Michael.
Selene e Michael giungono sul luogo indicato da Tanis e s'incontrano con Alexander Corvinus, appena giunto a Budapest risalendo il Danubio. Ha recuperato dalla salma di Viktor una delle due chiavi. Selene cerca di convincerlo a fermare Marcus, intenzionato a liberare suo fratello William (per dominare sul mondo con una nuova progenie creata da lui) ma Corvinus esita. Infatti, oltre ad essere il primo degli immortali, è anche il padre di Marcus (che fu morso da un pipistrello diventando il capostipite dei Vampiri) e di William (che fu morso da un lupo diventando il primo e il più feroce dei Lycan).