When Danny and his family are threatened by Thomas Wilder, a serial killer Danny has not been able to apprehend, Linda’s concern intensifies over her husband’s job as well as the state of their marriage. Also, Jamie challenges his superior officer, Sgt. William Mulvey, during a hostage situation.

When serial killer Thomas Wilder attaches a message to his latest victim that taunts Danny, their deadly game of cat and mouse becomes personal for Danny.

A NYPD whistle-blower claims there's been abuse of power within the organization, so Frank must investigate whether this is true. Meanwhile, Danny and Baez are suspicious of a car accident involving a pedestrian and think it may have been intentional.

An ex-NYPD officer goes missing the day after she reveals to Danny her plans to make amends to the woman she and her partner wrongfully convicted years ago. Frank faces a dilemma when one of his peers refuses to retire.

Erin faces off against her ex-husband in court when he represents the person she is attempting to convict of murder. Frank is confronted by a mother who accuses the NYPD of being negligent in solving her son’s murder. Jamie rides with a new partner.

After Reggie Wilson, a witness in a former case of Erin’s, asks her for help shutting down a drug operation in his apartment building, she makes it her mission to make the building safe for his family. Also, while investigating a teen’s suicide, Danny and Baez uncover information that suggests the death was a homicide, and Frank looks into potential misconduct within the Mayor’s office.

Danny and Baez investigate the murder of a single mother whose ex-husband has a history of violence. Also, Frank deals with the fallout when Mayor Dutton eliminates solitary confinement in prisons, and Jamie’s efforts to save a young woman who overdosed on drugs has unexpected consequences.