It's ten years since Mitch died and the sterility gas was unleashed. Abe, now a doctor, is trying to find a cure. Meanwhile, Jackson and his new girlfriend Tessa rescue refugees in Portland, Logan is a NYPD detective, and Jamie is trying to track down the Shepherd's leader before he unleashes a greater cataclysm. Meanwhile, an IADG team finds Mitch in an abandoned Russian lab.