Erin tries not to feel overpowered as her new boss shadows her at work just as she's trying to get a nervous eye-witness to reveal the identity of who shot her boyfriend. Also, the serial killer who previously held Danny and Baez hostage resurfaces, and when Jaime arrests an intrusive reporter who appears at a series of store lootings, it leads to a standoff between Frank and the Attorney General over the press' First Amendment rights.

Shockwaves ripple through the Reagan family when Danny discovers that their newest family member, Joe Hill (Will Hochman), is working undercover for the ATF to bring down a gunrunning organization.

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.

Danny and Baez race against the clock to catch a serial killer targeting young women; Erin and Eddie clash when Eddie intervenes in a murder case and Erin's personal life; Frank must decide how to discipline his grandson.