Eight centuries ago, a fierce blood feud erupted between the Vampires and Lycans. At the center of this conflict were two brothers: Markus and William, children of Alexander Corvinus, with Markus being the first Vampire and William the first Lycan. In the year 1202, an army led by the three powerful vampire elders—Viktor](/actor/bill-nighy), Amelia, and Markus (played by Tony Curran)—scheduled a confrontation in a village devastated by Lycans. Viktor insisted that William needed to be dealt with, fearing his volatile nature, but Markus could not permit his brother's demise. In a tragic twist, William's reckless actions had transformed an entire village into Lycans, prompting the Vampires to take drastic measures by burning the bodies of the infected.
When Viktor and Amelia captured William Corvinus (Brian Steele), the original and strongest werewolf, they faced opposition from Markus, who was protective of his sibling. Viktor commanded that William be imprisoned eternally in an undisclosed location due to his uncontrollable nature, a consequence of being the first pure werewolf.
In the present day, Selene (Kate Beckinsale) is determined to unveil the truth behind Viktor's death to the ancient vampire Markus, who remains in hibernation. Conversely, Markus has already awakened and seeks to free his brutal brother, William, from captivity. Haunted by his past, Viktor opposes the idea since the initial werewolves, like Lucian, were unable to revert to their human forms.
Selene takes Michael (Scott Speedman) to safety while plotting against the vampire regent Kraven (Shane Brolly), whom she suspects of plotting against Markus. Before Kraven can act, Markus irreversibly shifts the tide by awakening and eliminating him and his men in swift retribution.
As the dust settles, Lorenz Macaro (Derek Jacobi) commands a cleanup crew to survey the scene of the Lycan lair's aftermath. Investigating further, he uncovers the shocking truth behind Lucian and Viktor's demise, revealing Kraven's complicity in the betrayal. Among the findings, a metallic disc inside Viktor leads to a pendant once worn by Sonja, the other half now held by Michael after Lucian's death.
Utilizing knowledge obtained from Kraven's blood, Markus locates Selene and Michael in Hungary, attacking them. However, the pair manages to evade Markus's relentless pursuit and hides in a warehouse. In the midst of their escape, Michael impressively stands his ground in combat against Markus, who is fixated on seizing the pendant around Michael's neck. To shield Selene, Michael envelops her with tarpaulin from the truck and paints the windows black to block out the sun.
Meanwhile, Macaro diligently tracks their every move. In the warehouse, the tension between Selene and Michael escalates, allowing them to share heartfelt emotions culminating in passionate intimacy. Aware of Markus's determination to obtain the pendant, they resolve to uncover its true significance. Selene has a fleeting memory of the pendant from her childhood but remains oblivious to its real importance.
Their journey leads them to the exiled vampire historian Andreas Tanis (Steven Mackintosh), who divulges the shocking reality about Markus being the first vampire—the offspring of Alexander Corvinus, the first immortal. Markus's transformation into a vampire came from a bat's bite, while William's metamorphosis originated from a wolf. The third brother, human, fathered a lineage of mortals that includes Michael, the first Lycan-Vampire hybrid.
Tanis further enlightens Selene and Michael about the first werewolves, who were mere beasts without human form. Due to William's destructive capacity, Markus sought Viktor's assistance, leading him to transform Viktor and his army into vampires to combat William. However, Viktor's choices avoided the brothers' deaths due to fears of risking the vampire race's survival. Unbeknownst to her, Selene's father was the architect behind William's prison, with the pendant serving as the key. When Viktor killed Selene's family, he spared her life by transforming her into a vampire with the prison's location encoded in her blood.
Upon leaving Tanis, Markus arrives, drinking his blood to trace Selene and Michael, brutally killing Tanis in the process. In a shocking revelation, Selene and Michael discover that Macaro is, in fact, Alexander Corvinus himself, who has spent his eternal life protecting the secrecy of the ongoing Vampire-Lycan war. He firmly refuses to help Selene eliminate his sons. Just as Markus confronts Michael, the battle turns grim, and Selene's blood is used by Markus to reveal the prison's location before he fatally wounds Alexander, obtaining the other half of the pendant. Markus's ambition is clear: with William, he aspires to rule as a god-like master over vampire-Lycan hybrids.
At Alexander's urging, Selene imbibes his blood, boosting her strength and healing abilities to match that of a hybrid. In a self-sacrificial act, Alexander detonates a bomb aboard his ship, bringing about his own demise. Now equipped with newfound powers, Selene commands a helicopter to confront Markus, but she discovers that he had already liberated William.
The ensuing chaos leads to William infecting the cleaners who transform into wolves. Miraculously, Michael awakens, presumed dead, joining the fray in his hybrid form and ultimately slaying William. The climactic battle allows Selene to face Markus directly, ultimately ending his life by propelling him into the blades of a crashing helicopter.
In the aftermath, Selene realizes that Alexander's blood has gifted her with hybrid abilities, shielding her from the lethal rays of sunlight that would otherwise signal her end as a vampire.
