Five young and ambitious rookie cops continue to navigate the emotional trials and tribulations of their professional and personal lives. After two years on the job, these rookies are well on their way to becoming experienced cops. But at what cost? What price will they have to pay, both professionally and personally, to succeed at their jobs?
The theft of an armed police car tops the list of dangerous pranks as local schools wind to a close for the summer. While tracking down the stolen vehicle, Andy and Swarek pick up the trail of a hotheaded teen boy who robbed and unhappyly assaulted a notorious local criminal - who happens to be his girlfriend's father. Andy and Swarek must find the armed teenager before disaster strikes.
Dov's shooting of a young black teenager during a convenience store robbery in progress is called into question. With an angry community on the verge of rioting, an investigation must decide if Dov acted within guidelines or if he acted too quickly.
A two car accident involving a bachelorette party and a parked vehicle leaves one driver dead. The handling of the car crash turns into chaos for Traci's first day as a detective when it's discovered that the driver of the parked car was already dead before the accident. Traci and Andy discover a secret the bride would rather keep hidden, leading them to believe the murderer will strike again if they don't catch him. When Chris works with Gail on a case, he becomes aware that his feelings for Gail are still there but now he has competition.
When Andy responds to a domestic disturbance the social worker on scene is none other than Claire McNally, the woman who abandoned Andy and her father 15 years ago. Andy's issues with her estranged mother come crashing back as she's forced to investigate together with Claire this family's turmoil. The rest of the team hurry to find the missing mother and two children before anything disastrous happens. When recovered guns resurface on the streets, Detective Barber's badge is on the line.
When Andy and Swarek respond to a noise complaint, they find a stabbing victim and Oliver Shaw's teenage daughter, Izzy, at the scene. When Izzy goes missing, her involvement in the crime makes it difficult for Shaw to be both a good officer and her protective father.
The officers of 15 Division are about to get a reality check when they go to a so-called psychic to find a missing witness in an organized crime trial.
When a pattern emerges among several cases of missing women, Gail goes under cover to investigate; Dov and Chris discover a body, leading them to believe Gail is in danger.
When Dov and Chris discover a missing girl's body in a ravine, Detective Luke Callaghan returns to oversee the investigation; when the officers learn that Gail has been abducted, they rally to track down her captor.
The officers try to prevent dangerous fallout when a laptop containing sensitive information is stolen; a wedge is driven between Sam and Andy.
Andy and Nick investigate when a neighborhood drug lord threatens a priests life; a young drug runner's refusal to turn informant leads Traci to make a decision about her career; Chris and Swarek butt heads; Dov's relationship takes a dark turn.
With the rookies on their own during a turbulent night in the station, a prisoner pulls a gun on Chris. IA's inquiry into the incident leaves the rookies thinking about the choices they made that led to that night's events and about the fine line between telling the truth and having each other's backs. Meanwhile, Gail it still trying to recover from her traumatic kidnapping. And while Chris is caught unaware by a surprise, Andy learns a secret about Nick's past.
After a unhappy child abductor escapes custody, Andy and Dov find that he's taken another girl. Later, after Andy and Swarek confront the vicious pedophile, Andy has to choose between her professional life and her personal life. While family obligations have Chris considering a transfer, Gail and Traci are each confronted with significant career decisions.