In the series finale, Teresa gets a return visit from FBI agent Cuyler (Adam Arkin), and Jarek is determined to resolve some lingering issues that have plagued the Wysockis. Meanwhile, Teresa and Jarek play all their cards in their case against Gibbons.
A possible hate crime spurs Teresa to try to stop an unethical promotion system within the police force, but her daring actions awaken suspicion in Gibbons. Meanwhile, Vonda gets an anonymous package that makes Jarek confront truths about their family.
Teresa and Jarek face a surprising setback in their war against Gibbons when a crooked city official gets acquitted by a deadlocked jury. They look into the situation and find not only jury tampering, but other misdeeds as well.
The mayor faults Teresa for rising crime rates after five people are shot in Lincoln Park, and Teresa wants Jarek to find the shooters so she can rebuild her public image. Elsewhere, Isaac and Vonda must reinvestigate an old domestic-abuse case.
In the midst of a heat wave, Jarek and Caleb investigate a homicide in which a son witnessed his father's murder. Meanwhile, Teresa gets a new driver; and Gibbons seeks Liam's assistance with his constituents.
Jarek investigates a powerful drug dealer, but the FBI gets involved and causes problems. Elsewhere, Liam puts his cover at risk when he sympathizes with grieving families in front of Gibbons; and Jarek spends time with his ex-wife while his fiancée proceeds with wedding plans.
Jarek and Caleb try to track down a drug supplier whose merchandise put a wealthy family's son in a coma, and the investigation leads to the discovery of a complex murder. Elsewhere, Teresa wants to purchase new radios for the department.
A teenager's murder in Chinatown is investigated, and Teresa tries to get the locals to cooperate while Gibbons works on making headway with the area's unofficial mayor. Elsewhere, Teresa's brother-in-law enters a questionable business deal.
Jarek and Caleb try to stop a bomber who blew up a building and has plans for additional targets. Elsewhere, an armed teenager attempts to rob Gibbons, and this prompts the alderman to recall his own upbringing and youthful ideals.
The police seek revenge against a cop killer. Meanwhile, Gibbons pays his respects to the fallen officer's family, but he has an ulterior motive for his visit; and Vonda and Isaac join the organized-crime division.
In the series opener of this ensemble drama about Chicago cops fighting crime and political corruption, new police superintendent Teresa Colvin (Jennifer Beals) recruits one of her ex-partners (Jason Clarke) to head up a city-corruption task force. Chief among their targets is a city alderman (Delroy Lindo).