A severe heat wave wreaks havoc on the city, forcing the rookies to work around the clock to keep the peace. In the midst of the chaos, Andy discovers that a serial rapist may have resurfaced to prey on vulnerable teenage girls. And when the extreme temperature precipitates a citywide blackout, Andy finds she’s cut off from all backup and must take.

What was to be a routine day for Andy is abruptly put on hold when her ex-copper father, Tommy, confesses that he might have committed a serious crime during one of his alcohol-induced blackouts while settling a score that has tortured him for years. As she and Swarek try to piece together what happened, little by little she begins to uncover the truth about the case that sent her father over the edge – evidence that could possibly send him to prison.

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.

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.

While tracking down a police car stolen by students as a prank, Andy and Swarek pick up the trail of a teen who robbed and assaulted a local criminal.

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.

On her first day back, Andy is forced to work a bank robbery case with newly promoted Swarek; a distraught woman gives Nick perspective on his life with Gail; a bombshell is dropped on Noelle.

When Andy and Chloe respond to a routine 911 call, they are blindsided by an unseen shooter out for revenge.

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.

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