Triumph turns to humiliation when a high-stakes takedown of a suspect goes awry. Andy McNally has made a critical rookie mistake, ruining a long-running undercover drug sting, and tries to make up for it by going face to face with a volatile gunman who already has one man's blood on his hands.
As the other rookies attempt to hunt down a violent escaped convict, Andy gets a lesson in the dangers of undercover work when she and her training officer, Detective Sam Swarek, search for a missing informant whose cover has been blown. Swarek's rogue tactics on the job aren't all that Andy finds troubling -- there's also a surprising, undeniable attraction between the two of them
Andy wrestles with a dilemma, while the other rookies are ready to duke it out at a charity event.
Andy goes under cover as a prostitute during a citywide sting operation; Dov and Andy's attempt to impress Sgt. Boyko backfires.
Andy and Traci are among the first responders to a home invasion at an upscale address; when the crisis appears to be over, Traci hurries away to handle a personal emergency; Andy must confront the armed suspect alone.
A fatal traffic accident involving an elderly man and a cyclist may not be as open and shut as it seems, and Andy's romance with Detective Luke Callaghan also seems headed for a collision after she objects to how he handles a young murder witness with a bullet lodged in his head.
A heat wave makes life on the streets even more perilous for the rookies; the squad discovers that a serial rapist may be on the loose; during a blackout, Andy must take down a vicious predator alone.
Chris and Andy face a tough decision while investigating a vicious beating while Sam and Luke get competitive during a retraining exercise.
Chris and Gail's investigation into a messy highway accident leads to the discovery of a license plate matching an Amber Alert for a missing nine-year-old girl. Division 15 embarks on a massive manhunt to find the girl and the car's missing driver. Meanwhile, an intense interrogation of the parents uncovers disturbing evidence. More secrets unravel, as the entire division races the clock to find the young victim - hoping it's not too late.
An inmate escapes during a prisoner transport. Gail and Dov try to help a man with amnesia. Traci and Chris help reconstruct notes missing from a court case.
After stumbling on gruesome evidence that Andy's ex-cop father may have committed a murder during a drunken blackout, Andy and Swarek furiously search for proof of his innocence. Meanwhile, Chris and Dov show they're not superhero crime fighters when a masked vigilante dressed like a caped crusader robs their squad car and the unintentional consequences help a drug dealer.
It's judgment day for the rookies, who soon will learn whether or not they've passed their evaluations and can keep their badges. Before she hears her fate from Staff Sgt. Frank Best, Andy has a harrowing experience involving the suspicious death of an unidentified girl that causes her to consider leaving the force.
When Andy and Chris make an untimely arrest, they unknowingly compromise a major drug bust. Andy steps up, attempting to salvage the operation by going undercover with Swarek, but a critical change in plans puts both of their lives in danger. Back at the station, Dov learns more about his girlfriend than he wanted to know - forcing him to chose between police work and his love life.
Andy's world explodes when a fresh-faced university student is caught in the crossfire during a random concert shooting. Devastated by the seemingly senseless act of violence, she sets out to unravel the motive and track down the shooter -- putting her in direct conflict with Division 15's new detective, Jo Rosati. Meanwhile, as Rosati investigates her own angle on the concert mayhem, sparks fly between her and her former partner, Detective Luke Callaghan.
Andy and Gail go undercover as cocktail waitresses to clean up a drug-infested club, but get more than they bargained for when their fellow waitress turns out to be involved with a vicious criminal. Meanwhile, Traci wrestles with feelings for her old flame, Detective Barber, Dov tries to weather the storm when a young woman files a complaint against him, and Andy unwittingly opens up to Sam about her commitment to Luke.
As a full moon hangs over the city, the rookies are unnerved by a series of strange occurrences. While investigating the bizarre theft of three severed heads from a medical lab, Andy and Swarek track a disturbed man whose obsessive behavior makes him suspect. In an effort to protect the life of a young woman who may be the next target, Andy places herself - and, inadvertently, Luke - in a potentially fatal situation.
As the 15th Division attempts to recover from an explosive event involving one of their own, a series of arsons culminates in the torching of a laundromat. The list of suspects grows, as Chris and Gail take to the streets and encounter a man from Chris's past, while Traci interrogates a young firebug found at the arson scene. Meanwhile, Andy's effort to stop the grieving widow from entering the burnt-out laundromat results in the two women being trapped in the unstable building, and what seems like a straightforward case of arson ends up being something much bigger.
A local car dealership is the backdrop for a Division 15 sting operation to crack down on suspects with outstanding warrants. However, when one of the captured criminals tries to bargain for a lighter sentence by offering insider information to Dov and Chris, it puts them in peril in a booby-trapped meth house. Meanwhile, Jo convinces Luke to help her on a high-stakes surveillance job. Trapped together in a hotel room, the two detectives finally have it out over their past, raising the question of whether they are really finished.
When a police informant's murder points to the involvement of the notoriously brutal East Jameson gang, the division realizes that cracking this case will not be easy. And when Gail's intimidating mother, Superintendent Elaine Peck, arrives on the scene, there is even more pressure to solve the case. Meanwhile, Andy finds herself paired with Detective Rosati, whose unintentional disclosure of a secret puts Andy's relationship with Luke in jeopardy. And Gail, stressed out by her mother's presence in the station, is assigned to protect the only known witness to the crime -- a seemingly homeless eight-year-old boy with a shocking secret of his own.
Andy is worried that her personal problems are clouding her professional judgment when a woman is brutally attacked on her watch. Detective Luke Callaghan is convinced that it's the same suspect when the details of assault are alarmingly similar to the unsolved murder of a rookie. Ironically, Andy is caught in between dueling theories of the crimes - one supported by Luke, the other by Jo Rosati. But when Luke is booted from the investigation because of erratic behavior, he tries to get Andy to follow through on his hunch - putting her in serious danger.
Division 15 is thrown into a panic when a seemingly drunk man that Gail and Traci brings in collapses from a mysterious illness and everyone is placed under a quarantine. Meanwhile, Andy and Swarek team to apprehend and book an unusual suspect in a brutal bank robbery - a man covered with blue dye. But will they uncover the identity of his violent partner? And as time ticks down, the squad grows increasingly nervous about the quarantine, with Gail worrying about her exposure to the sick man. Also, Dov's first date with a sexy bomb technician ends in a thrilling takedown.
It's a race against the clock as Dov and Gail work under Swarek's expert tutelage in a stakeout operation to stop an Asian gang from killing a snitch. Meanwhile, at Mounted Unit training day, Andy and Chris join the rookies from Division 27 in a competitive equine training event that gets Andy back in the saddle - both personally and professionally.
In the course of pursuing a kidnapper, Andy and Swarek come upon a terrible accident with a woman pinned in her car. While Swarek tracks the missing child and his kidnapper, Andy stays behind with the critically injured woman. The rest of the 15th Division gets in the chase to catch the kidnapper, but Chris comes to blows with Dov over an indiscretion involving Gail. Meanwhile, Andy is galvanized to take bold action when she realizes life may be passing her by while she is making other plans.
Andy, Dov and Traci are tested with a challenging undercover training exercise, but things go awry when Andy and Traci run into Swarek on his own undercover operation, and they must tread carefully not to blow his cover. The women stumble on a young woman who is overdosing and risk blowing their own cover to save her life. Meanwhile, Dov finds himself on a "ride-along" with a drug dealer who was an old friend of his dead brother's, and faces a choice that could threaten his career. Back at the station, Chris and Gail deal with a teenage boy they found tied up at a graveyard, but must sift through the wreckage of their relationship to get to the bottom of a bullying situation.
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.
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? And how can they stay true to themselves - maintaining their individuality and compassion - along the way? While a new rookie has joined 15 Division -- ex-soldier Nick Collins, who is trying to adapt to civilian policing after serving in Afghanistan -- the rest of the rookies are now entering their third year on the job. They have overcome the sophomore curse: that a little knowledge is a dangerous thing. However this year, the rookies of 15 Division are going to have to learn to be careful what they wish for - and they are going to learn it the hard way.
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 violently assaulted a notorious local criminal - who happens to be his girlfriend's father. Andy and Swarek must find the armed teenager before disaster strikes.