Andy considers leaving town for four months on an undercover assignment as she struggles to deal with the birth of Sam and Marlo's baby; and Jarvis reveals the shocking news that 15 Division will be restructured following the corruption scandal.
The officers try to move beyond the corruption scandal; at the same time, a heat wave hits and Jarvis opens 15 Division to the public as a cooling station. Elsewhere, Andy helps a very pregnant Marlo track down a volatile woman who went missing after group therapy; and Oliver returns to work as a street cop.
IA suspects Oliver of corruption, which leads Andy, Dov, Gail and Nick to undertake a risky and potentially career-ending plan to prove that it's Commissioner Alonso Santana who is the guilty party. Meanwhile, Traci shadows Steve Peck, hoping to calm her fears about his involvement in the bombing.
Andy and Sam are shocked to learn that Oliver is the prime suspect in IA's corruption investigation into 15 Division. Determined to prove their friend's innocence, they go rogue to track down the missing explosives dealer who can clear his name. Meanwhile, an oblivious Oliver has his hands full with a sensitive missing child case.
A community-outreach baseball game is interrupted when two of the players are wounded in a drive-by shooting. Although it appears gang-related, Gail's instincts tell her otherwise, putting her relationship with her older brother Steve to the test. Elsewhere, Sam's plan for the perfect getaway with Andy to Oliver's cabin encounters all sorts of setbacks.
Traci is a no-show at her first raid, which leads her compatriots at the 15 Division to believe she must have been kidnapped by the notorious gun dealer they are after. As they work to find her, Andy and Gail come to another frightening conclusion with the realization that a serial rapist could be to blame for Traci's disappearance.
Juliet has reason to worry about Nick, whose estranged older brother, Finn, shows up with information about the drunk driver who killed their parents 18 years ago. Elsewhere, Dov and Chris kick some criminal butt when they take down a wanted MMA fighter.
A riot breaks out at a women's correctional institute while Andy, Juliet, Nick and Gail are there to transfer prisoners. When the facility goes into a complete lockdown, two of the 15 Division officers find themselves trapped with a dangerous inmate who is desperate to prove her innocence. Elsewhere, Sam shows up at Marlo's ultrasound.
Andy debates her future with Sam after learning that Marlo is pregnant with his baby; at the same time, she meets an out-of-control teen who needs to be protected from her own conservative family. Elsewhere, Juliet is paired with Nick for her first shift at 15 Division.
In the Season 6 premiere, Andy and Sam return to work following a much-needed vacation after the evidence room bombing. But before long, life throws them another curveball when an intruder attacks a member of 15 Division and the Sex Crimes Unit steps in to take control of the case.