The strigoi are evolving, becoming faster. Smarter. Eph's bioweapon is failing. He struggles to improve it 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 it. 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.
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.