The story of Windy City's Police Department in Chicago.
Cast: Don Kress, Andre Bellos, Jason Beghe, Sophia Bush, Patrick John Flueger, America Olivo, Jon Seda, David Aron Damane, Zach Garcia, Laroyce Hawkins, Heidi Johanningmeier, Christopher Kahler, Kurt Naebig, Emily Peterson, Joe Reegan, Matthew Sherbach, Isaac White
Atwater goes undercover to take down a gun-trafficking ring, but discovers an officer from his past is undercover in the same organization.
The clock is on after Ruzek witnesses a woman's kidnapping and the team races to put the pieces together. Burgess tries to connect with Ruzek outside of work but he mysteriously distances himself from her.
Intelligence does everything they can to build a case against the elusive leader of a drug ring, but things get complicated when Rojas realizes someone she cares about might be involved.
Voight enlists the help of a reformed gang member to get a key witness' testimony in a murder case. More lives are put on the line as a gang war brews.
An armed robbery case quickly turns into a homicide investigation. When one suspect's background suggests domestic violence, Upton is forced to reckon with her childhood. Voight and Halstead butt heads over Halstead's righteous instinct.
Intelligence searches for the dealer who caused multiple overdoses and is connected to Roman's missing sister. The case becomes a homicide investigation when they find the dealer's dead body.
A homeless man's murder leads Intelligence to a criminal who has evaded capture for years. Rojas has a troubling experience with a young mentally ill man.
After receiving a distressing 911 call, Burgess enlists the team's help to track down a girl caught up in a sex-trafficking ring.
Voight makes a deal with Darius Walker to help bring down a rogue group of dirty cops dealing drugs that were supposed to be destroyed. Upton clashes with Voight and enacts her own form of justice.
Ruzek and Burgess's secret begins to have severe implications for their police work. A series of deadly acts of vandalism causes tensions to run high in the insular neighborhood of Canaryville. Atwater tries to reach out to his brother, but only pushes him further away.
As they await news of Halstead's fate, the team tries to focus on work, turning their attention to an illegal arms dealer. Atwater discovers his brother, Jordan, is back in Chicago and could be tied to the case. Voight faces the tricky task of how to deal with Halstead's shooter. Burgess finally makes her decision.
Halstead's secret ongoing relationship with a woman connected to another case puts him in jeopardy. Fall Finale.
After injuring herself while pursuing a suspect, Burgess receives a shocking diagnosis. A homicide case turns into a missing persons case, with a sinister twist. Voight has to decide between justice and the letter of the law.
Voight pulls Darius in after Crawford asks Intelligence to investigate a dangerous drug, but there is little trust in the relationship. When their plan to nail a dealer goes awry and another CI is murdered, the team must make a tough decision about Darius.
The shocking murder of young boys affects Halstead. Crawford encourages Intelligence to use a new facial recognition software to help identify a suspect, but the plan backfires.
A murder in a Bulgarian neighborhood results in a challenging investigation when locals won't talk to police. Ruzek has a clash with a patrol officer.
After zeroing in on a suspect responsible for bioterrorism, the P.D. prepares to undertake their biggest manhunt yet. Upton is torn between helping track down the perp and providing emotional support to a scared young girl who needs her..
After a botched carjacking turns out to be something much bigger, Voight's unit goes toe-to-toe with a smart drug kingpin who only works with women. New recruit Vanessa Rojas struggles with the transition from undercover to Intelligence.
When Atwater goes undercover in a drug syndicate, he learns there may be more to its kingpin than meets the eye; Halstead tries to join Atwater undercover, but finds himself at a disadvantage.
When Kelton is found murdered, Voight's grudge against the mayor-elect puts him under suspicion. Upton and Halstead are eager to prove their sergeant's innocence, but the more evidence they gather, the closer they come to doing the opposite.