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.

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 in the Mayor's office.