Eph and Nora work on a biological weapon to kill 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.

Eph and Nora experiment on their newfound patients. Fet and Dutch grow closer as they clear out the neighborhood buildings, and Kelly begins her hunt for Zack.

Gus and Vaun wage an attack on Palmer as Eph struggles to connect with Zack. Councilwoman Justine Faraldo vows to bring her extermination policies to the other boroughs.

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 changes his appearance to leave the city while Nora is left as the reluctant parent for Zack. Dutch and Nora make a deal with Justine to secure Fet's release from jail.

Eph concocts a plan to make and distribute a bioweapon. Gus realizes Angel can be an unlikely ally, and Kelly comes after Nora and Zack.

Setrakian and Fet use Fitzwilliam's info to attack the Master. Eph returns to NYC frustrated but energized to go after the one person responsible for killing 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.

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.

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.