After getting a match from an unknown relative from a DNA network, Sean Reagan does some detective work to figure out who this mystery person might be. Frank gets a personal request from a woman to transfer her son to a safer assignment. Also, Danny seeks to uncover the truth behind the murder of a key witness in one of Erin's cases, and Eddie begins to think about having a child after she and Jamie discover a newborn left outside their precinct.

Frank and Garrett quarrel when Garrett refuses to walk back a quote he provided to a local newspaper. Also, Danny and Baez discover a connection to a feud between local residents and city-sponsored hotels for the homeless while investigating a murder, Anthony is mistaken for a mafioso and Eddie pressures Jamie to take a love language quiz.

Frank is at odds with his friend Archbishop Kearns when he says the NYPD arrested the wrong man for a murder; Eddie tries to get justice for a sexual assault survivor; Jamie and his nephew, Joe Hill, butt heads over fair police practices.

Frank, Baker, Garrett and Gormley experience feelings of guilt when Detective Angela Reddick (Ilfenish Hadera), an officer they briefly worked with at 1PP, is shot after Frank reassigned her for not meshing with their team. Also, Eddie, Danny and Baez investigate a man’s murder after Eddie and her partner respond to an altercation between the victim and a neighbor, and Anthony finds himself at a crossroads when he’s offered a promotion that strains his relationship with Erin.