Harlee navigates her fractured relationship with Wozniak, as she struggles to conceal her deepest secret. Following his discovery that Harlee collaborated with the FBI, Wozniak is confronted with a gut-wrenching dilemma of his own. The crew is under tight scrutiny from Stahl and the FBI as well as from Internal Affairs. Meanwhile, a former member of their crew, Julia Ayres, runs for mayor and neither Harlee nor Wozniak anticipates that Ayres’ corrupt connections will trap them in a dangerous war with the Mafia.

Six months after dual near-death experiences, Harlee and Wozniak have radically different reactions to their respective traumas. Harlee attempts to start anew, but she is still haunted by visions of rogue FBI agent Stahl. Meanwhile, Wozniak embarks on a vengeance quest, driven to reclaim both his standing and domain of small-time corruption and effective policing. At this existential crossroads, the crew responds to a midnight massacre that proves to have deep roots within the untouchable and corrupt Intelligence Division of the NYPD, headed by Capt. The crew walk a tightrope between justice and shielding a malevolent force within the NYPD, drawing Harlee toward the crucible of her life.