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.

A bomb explodes in a parking garage. The 15 Division must stop the suspect.

The officers of 15 Division work to track down Ted McDonald. But even after catching him, they realize Ted has more targets set to explode out there. The clock is ticking…

The officers try to prevent dangerous fallout when a laptop containing sensitive information is stolen; a wedge is driven between Sam and Andy.

In the aftermath of the night's traumatic events, Andy and Dov try to pull themselves together at an all-night diner, but are caught off-duty and off-guard in a volatile diner hold-up. Meanwhile, the weary officers at 15 Division struggle to contain the evening's collateral damage under the watchful eye of a tough new Inspector.

Strange happenings and a full moon rattle the rookies. Andy and Sam investigate the theft of some severed heads from a medical lab. A particular man catches their attention as a suspect with his obsessive behavior. While trying to protect a young woman who could be the next target, Andy puts her life and Luke's in jeopardy.

When Traci and Andy are sent out on an undercover training exercise, they stumble upon a young woman who is about to die of an overdose. Meanwhile, Dov finds himself on a “ride-along” with a drug dealer and old friend of his deceased brother. Back at the station, Chris and Gail deal with a teenage boy they found tied up at a graveyard; sifting through the wreckage of their relationship, to try to get to the bottom of a bullying situation.

As the officers of 15 Division try to hunt down the killer of Brian Gowdy, Andy and Sam go on the road to interview a list of inmates at Millburn Penitentiary. All are known associates of the prime suspect; one person on that list happens to be none other than Jay Swarek, Sam's elusive father.

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.

A violent pedophile escapes during an emergency hospital visit and abducts a girl; Andy faces a serious decision; Chris considers a transfer.

When a tenement-building shooting leads to the discovery of an executed gang leader, 15 Division must race to find the killer before a gang war breaks out. As the murderer zeroes in on the one witness who can tie him to the crime, Andy and her rookie, Duncan, are put to a life-and-death test of true police heroism.

Dov suspects Chris isn't ready to get back on the right track; Steve tells Traci he's about to raid a gambling den frequented by her husband.

After a three-month suspension, Andy faces an official tribunal that will decide if she should be reinstated; a drunken driver (William Shatner) with a grudge against the police causes a multicar crash.

When Dov walks into a robbery in progress and shoots a black teen, the community calls for him to be investigated.

Oliver Shaw's teenage daughter, Izzy, witnesses the brutal stabbing of a homeless squatter; when Izzy goes missing, officers rush to track her down.

When 15 Division goes undercover at a club-land bar that's a possible hub for illegal handguns, Chris's erratic behaviour and concern for a specific drug dealer make Dov suspicious. Meanwhile – after learning Duncan has made serious professional allegations against her – Andy decides to help Sam with a missing person's case that takes a dark turn.

When the Division helps tenants move out of a condemned subsidized-housing complex, they discover a badly beaten man in one of the empty units.

A home invasion at an upscale address leads to a massive first response call that brings out the training officers in full force. After the scene is cleared, Andy and Traci remain behind with the terrified homeowner. When Traci is called away to deal with an emergency with her son, Andy is left alone to face the armed thief who is still prowling around the house.

Andy's world explodes by a seemingly senseless act of violence during a concert shooting. When she sets out to unravel the details, she comes into direct conflict with Luke's former partner, Detective Jo Rosati, a new detective with Division 15. As Rosati investigates the case, sparks soon fly between her and Luke.

The torching of a Laundromat is the latest in a series of arsons which the 15th Division must work. The list of suspects is long so Chris and Gail take to the streets while Traci interrogates a person found at the scene. Andy is left to deal with the widow who insists on entering the burnt-out building which ends with the two of them trapped inside.

Detectives Callahan and Rosati are at odds over how to correlate and interpret the facts of two vicious crimes. Luke feels strongly that the latest woman attacked on her watch is connected to an unsolved rookie's murder, but his erratic behavior gets him kicked off the case. Andy may be in serious trouble when Luke urges her to follow through with his hunch on the crimes.

Gail and Traci apprehend a man who mysteriously collapses at the station which in turn places Division 15 under quarantine. Andy and Swarek are after a brutal bank robber and his partner but it will take some out-of-the-box thinking to solve this crime. Dov goes out on a first date with the bomb tech who saved his life.

While working a kidnapping case, Andy and Swarek find themselves on the scene of a car accident. As Swarek and the rest of Division 15 pursue the kidnapper and missing child, Andy remains at the scene with a woman trapped in her car. A transgression involving Gail puts Chris at odds with Dov. Andy concludes that it's time to re-evaluate her life.

When Gail’s uniform is stolen from her car, she and the other rookies from Division 15 attempt to catch a cop-impersonating vigilante. A drug deal gone awry may offer clues to help Chris and Dov unravel the motive behind the cop masquerade. Meanwhile, Andy and Sam’s inability to stay away from each other poses a life-threatening risk to Swarek.

Blaming herself for Swarek’s mysterious disappearance and fearing for his life, Andy struggles to find a lead in the case. Will Andy and the other rookies find him in time? Little do they know that shocking events triggered by this investigation will incriminate one of their own and may also put an end to Andy’s career.