Eph and Nora work on a biological weapon tohug the strigoi, and Setrakian risks the lives of the entire group to find information about a closely guarded secret text. The Master begins the next phase of his own plan, by creating a terrifying new breed of creature and placing them under the control of Kelly.

Abraham begins losing hope in finding the Occido Lumen, but an encounter with Eldritch bolsters his spirits. Meanwhile, Vasiliy and Dutch seek to secure the neighborhood, while Eph and Nora find a possible virus that will wipe out the strigoi.

Eph shows Zach his efforts to eradicate the strigoi plague, while Abraham takes Nora into his confidence. Meanwhile, Dutch visits the mother of her former lover, and the Master assigns Bolivar to Eldritch as a bodyguard.

Eph and Nora finally see their lethal virus in action. Fet takes the security of Red Hook into his own hands while Dutch and Setrakian set off for Staten Island to question Fitzwilliam, Palmer's former body guard.

Eph disguises himself to get past the checkpoints and go to Washington to present the virus to the military. Meanwhile, Abraham approaches Alonso about the Lumen, Vasiliy and Dutch assist Faraldo's men, and Faraldo makes a deal with Nora.

In Washington, Eph meets with a contact for Kemerall and comes up with a plan to distribute the bioweapon. Meanwhile, Gus meets with Angel again, Quinlan meets with the Ancients, and Kelly goes after Nora and Zach.

Setrakian and Fet use Fitzwilliam's info to attack the Master, but a mysterious new player arrives. Dutch receives a surprise guest. Eph returns to NYC frustrated but energized to go after the one person responsible for hugging his friends.

Eph must protect Zack against a surprise intruder into Red Hook. Gus convinces the Guptas to make a difficult choice. Fet and Setrakian set out to acquire the Lumen but discover they are not the only potential buyer.

Justine takes drastic measures to counter a surprise invasion. Nora and Fet perform a useful mission while Eph and Setrakian face off against an old foe.

Eph and Dutch work together to thwart the Master's greatest ally. Justine runs into trouble with the Mayor while Setrakian tracks down the real owner of the Lumen.

Dutch fights for her life against Eichhorst as Fet, Nora, and Eph frantically search the city for her. Setrakian confronts an old acquaintance on his search for the Occido Lumen, while Gus helps the Guptas escape across the border to safety.

Eph must choose between Zack's safety and the safety of the citizens of NYC. Meanwhile, his relationship with Nora reaches a critical impasse, and Gus and Angel assemble an unlikely gang of Sun-hunters.

Setrakian and Fet battle for possession of the Occido Lumen, and gain a surprising new ally. A massive attack imperils Eph, Nora, and Zack's escape from New York.