The strigoi are evolving, becoming faster. Smarter. Eph struggles to improve his failing bioweapon while trying to work through the emotional fallout of the abduction of his son, Zack. As Setrakian and Quinlan attempt to crack the Lumen's deepest-held secrets, Fet helps a Navy SEAL team in a deadly mission: search for the Master through the underground tunnels of New York.

The Master’s offer to return Zack plagues Eph as he considers taking the deal. Dutch reunites with an old group of friends but begins to question if her safety is better with them or with Fet, Eph and Setrakian. Palmer strives for answers to Setrakian’s secret strigoi blood treatments and discovers he may have a way to acquire it.

The Occido Lumen is gone. Stolen. Setrakian and Fet race to recover it. Gus and Angel try to hide a secret houseguest while avoiding a police sweep, and Quinlan's thirst for vengeance is revealed.

Things have changed. The infection enters a new phase. Fet wants to celebrate, but Setrakian and Eph are worried there's more work to be done. Justine conscripts a new, unwilling army in the fight while Eichhorst angrily lashes out with a plan to strike back.

New information from the Lumen forces Setrakian to seek help from his lifelong nemesis, Eldritch Palmer. Eph's new experiments to understand strigoi communication seemingly take him to the brink of madness while Fet is on a mission to discover strigoi movements across New York City.

Fet strikes hard at the heart of the strigoi army while Justine embarks upon a risky mission to drive the strigoi out of Manhattan once and for all. Gus and Angel fight for their lives and their freedom but are faced with a moral dilemma.

Setrakian offers hope in a new plan to trap the Master while Eph and Dutch seek out the Master's “voice.” Palmer needs Setrakian's access to the white to hold up his end of their bargain.

The Master's voice proves to be more powerful and potentially fatal than Eph or Dutch anticipated. Fet and Setrakian track down the cargo from the Egyptian vessel and realize they may be in over their heads. Quinlan strikes a deal with the Ancients, but a last minute betrayal proves deadly.

NYC is falling. Eph and Dutch frantically race to finish their new device to stop the Master before the city is overrun. Justine, Gus, and Angel fight in one last stand to stop the spreading virus. Palmer extracts vengeance for past wrongs but may have crossed the line.

Humanity teeters on the edge of destruction. The Master finally reveals himself, initiating the end game of a battle in which there can be only one winner. Eph, Fet, Setrakian, and Dutch must overcome their personal differences in a last-ditch effort to vanquish the strain.

Out of the ashes of humanity’s nuclear war, Night Eternal has begun. Haunted by the atrocities committed by his son, Eph abandons NYC for Philadelphia. His solitude is cut short when he encounters new fighters who rekindle his drive to fight back. Tasked by Setrakian, Fet and Quinlan search for a new means of stopping the Master.

Imprisoned as a subject in a strigoi breeding program, Dutch is desperate to escape and find Setrakian. Gus recruits his cousin for the inside job that will put his gang at the top of the new world’s underground economy, but Creem is suspicious of his business partner’s ambitions.

Quinlan and Fet discover that stealing a nuclear warhead isn’t easy when they encounter an unexpected enemy. Eph and Alex concoct a new weapon to use against the strigoi. Frustrated with his seclusion, Zack discovers a love interest.

Dutch is forced to make a deal with Desai, while she plots to escape a strigoi breeding facility; Eph and Alex seek to uncover the dark secrets behind the Partnership's new plan; Gus and Creem face off against a gang encroaching on their turf.

Fet and Quinlan track a convoy carrying their prized nuclear weapon; Eph and Alex search for clues to uncover the Master's plan for the fate of the human race; a familiar enemy traps Dutch, who encounters an old friend as well.

Fet and Quinlan must figure out how to get the nuclear bomb back to New York, while a desperate Eichhorst draws near; love-struck Zack tries to learn more about his new crush, but makes a devastating discovery.

With his health failing, Setrakian ignores Eph's warnings and pushes himself to the limit in his quest for victory and revenge; Fet and Quinlan race back to Manhattan, while the Master seals off the city and prepares to eliminate them all.

Reeling from loss, the heroes regroup; the heroes devise a new plan to track the Master through human collaborators, beginning at the blood farm with someone Dutch knows all too well.

An unexpected guest brings old conflicts to the surface, dividing the heroes and threatening the group's trust; with questionable new intelligence in hand, the group launches a make-or-break final assault on the Master.

In the series finale, Quinlan devises a desperate plan, but the costs are enormous. Eph wrestles with his conscience, Fet undertakes a suicide mission, and Dutch and Gus dig in for battle as humankind makes its final stand against the Master and his Strain.