This latest installment in the Underworld franchise picks up six months after the events of Underworld: Evolution. The story centers around the vampire Selene, who becomes a victim of the brutal human-led crusade known as "The Purge," aimed at decimating vampires and lycans after their existence is revealed. In this conflict, humans derogatorily refer to lycans as "Non-Humans" and categorize vampires as "The Infected."
Fast forward twelve years later, and the aftermath of human-led genocides against both races is stark. The once-thriving populations of vampires and lycans have been reduced to mere shadows of their former selves, forced into life as outlaws and scavengers. Tragically, 90% of the vampire race has been wiped out. Selene emerges from her cryogenic sleep, having been held captive by the medical organization Antigen, which seeks to develop an antidote for the virus responsible for creating both vampires and lycans. After regaining her freedom, Selene is plagued by ominous visions, which she believes are connected to her lost love, the half-vampire, half-lycan Michael Corvin.
Her search for Michael leads her to an unexpected ally named David, another vampire. Their conversation is interrupted by another vision, guiding Selene to a girl known only as "Subject 2," later revealed to be Eve, Selene and Michael's daughter who is a hybrid. Eve has suffered injuries inflicted by the lycans, and despite her condition, David quickly brings them to his coven for refuge. However, the warm welcome is short-lived as David's father, Thomas, delivers shocking news: Michael has been dead for twelve years, and the destruction of the vampire race rests heavily on Selene's shoulders.
To Selene's relief, after being administered vampire blood, Eve heals at an astonishing rate. The real danger emerges as Dr. Jacob Lane, director of Antigen, alongside his son Quint, is revealed to be a lycan as well. Their goal is not to create a cure, but rather to make lycans immune to silver and enhance their strength, with Eve's unique genetic code as the key to their sinister plan. David, aware of the impending threat, attempts to rally the remaining vampires for defense while Thomas insists on evacuation. Unfortunately, their contradictory strategies put them on a collision course with a powerful lycan attack that leaves their coven decimated.
Amidst the chaos, Selene faces off against a formidable opponent—a massive "super lycan" who turns out to be Quint, enhanced through experimentation with Eve's blood. Overwhelmed, Selene is knocked unconscious, and in a desperate measure, Thomas sacrifices Eve to the lycans in an attempt to secure their retreat. Following the mayhem, David is severely injured, and Selene resolves to rescue Eve. She saves David by giving him her immortal blood, a gift bestowed upon her by Alexander Corvinus in the previous installment.
With newfound determination, Selene enlists the assistance of Detective Sebastian, a human affected by the Purge who has a tragic past of his own, having lost his wife during the brutal campaign. Together, they hatch a plan to confront Antigen, permitting Selene to wreak havoc on their headquarters using explosives and silver gas, ultimately forcing Dr. Lane to relocate Eve for an operation.
In an action-packed sequence, Selene discovers Michael's cryogenic cell and releases him before a high-octane chase unfolds. However, Dr. Lane isn't without defenses, and a climactic battle ensues. Entrusted with Eve's fate, Eve taps into her hybrid strength, facing off against Dr. Lane after he augments himself with lycan enhancements. Her allies, Sebastian and David, join in the struggle, leading to an explosive confrontation that claims the life of the corrupted doctor.
In the midst of this turmoil, Selene's path leads her to confront Quint in a final showdown, where she utilizes cunning strategies to outmaneuver and ultimately eliminate him. Yet, with the dust settling, Selene finds only an empty cell where Michael was held. As the story concludes, Selene vows to locate Michael and reclaim their world, sparked by a grave realization of the war humans have declared. She is determined to bring hope back to the vampires and restore their rightful place.
