After six months working undercover, Andy and Nick's operation goes sideways when Nick - then Andy - go missing. Meanwhile, a random arrest at 15 Division puts Sam Swarek and the other officers in the middle of the investigation-turned-rescue-mission.
Andy is partnered with Swarek's new girlfriend, Officer Marlo Cruz. When they come face-to-face with an out of control EDP [Emotionally Disturbed Person], their differences are put to the test and one of them has to pull the trigger.
Andy has her sights set on a much-needed long weekend. But when a routine highway check leads to the discovery of a teenage boy in the trunk of a car, Andy and Gail must convince him that no heartache lasts forever... in order to save him from making a tragic mistake.
After a messy drug arrest, Andy and Marlo are quarantined together. Meanwhile, 15 Division springs into emergency response mode in order to get the contaminated drugs off the streets before a deadly outbreak sweeps through the city.
When a young woman is reported missing, the officers of 15 Division soon discover a possible copycat connection to one of their division's most distressing cases. With the clock ticking, Gail must face her worst fears in order to track down the missing girl.
When human bones found in a ravine open up a 15-year-old missing persons case, Swarek reunites with his old training officer to solve the case. In the process, Swarek gets a closer look at his mentor and must decide whether he wants to continue to follow in his footsteps.
Everyone at 15 Division, especially Andy, just wants a quick, smooth shift so they can get to Frank and Noelle's wedding. But things get complicated when they get called to a hijacked casino bus full of senior citizens... and when the bride, Noelle, goes missing.
When Chris returns for a visit, his reunion takes a shocking turn when his son, Christian, is abducted while under the care of Andy and Nick. It quickly becomes all hands on deck at 15 Division to find the boy - but even getting Christian home can't spare Chris from a startling revelation that may tear his family apart.
Near the end of shift, 15 Division busts a marijuana grow-op - a case that becomes Traci's first homicide and forces Andy, Nick and Gail to work overtime. Meanwhile, Swarek, Oliver, Chris and Dov head off to Oliver's new cabin for a confessional day of generator repair and male bonding.
When a suspected pedophile is found beaten within an inch of his life, Andy discovers Marlo has been conducting a mania-fueled, off-hours "investigation" into the man for days. Andy and Swarek must scramble to cover for Marlo's unprofessional conduct and find the real assailant, before Marlo is exposed.
After Andy and Chloe take fire from an unseen shooter, the officers realize they are the targets of someone with a grudge against 15 Division. They must continue to serve and protect while in the line of fire.
In the wake of a targeted attack on the officers of 15 Division, Andy, Swarek, and their fellow officers have to piece together the truth about a past crime in order to find Oliver Shaw - in time to save his life.