In the series premiere, Teresa Colvin, Chicago’s city’s first female superintendent, lobbies for a city corruption task force to investigate city politician Alderman Ronin Gibbons. Meanwhile, Colvin’s ex-partner and larger-than-life veteran of the Chicago Police Department, Jarek Wysocki investigates a suspicious murder in Grant Park alongside his new partner, Caleb Evers. Also in Jarek’s charge are his niece, Vonda Wysocki; her hotshot partner, Isaac Joiner; and low-life Liam Hennessey, an Irish thug who blends in with the gritty world of local crime. Together, these cops stop at nothing navigating the Windy City’s underbelly to fight crime and bring down Alderman Gibbons’ empire of corruption.

Following the shocking events related to a fallen officer, Teresa and Jarek vow to bring whoever is responsible to justice. In the meantime, Alderman Gibbons pays a visit to the victim’s family to offer his condolences and plant a few seeds of betrayal, implicating members of the Chicago Police Department. As every officer in the city hits the streets to avenge this cop killer, Jarek and Caleb follow up on some of Liam’s leads, while Vonda and Isaac are promoted to the organized-crime task force.

Jarek and Caleb arrive first on the scene at a bank robbery and chase the thief through the streets of Chicago only to find he has met a gruesome end. As the Chicago Police Department pieces together the clues of the robber, Superintendent Colvin conducts a critical meeting with Alderman Gibbons about a key construction site. Duplicitous politicking raises the stakes and further exposes the depth of corruption in the city.

After a bomber blows up a city building, additional targets and innocent people remain in danger. Teresa handles the escalating crisis, as Jarek and Caleb race against time to track down the suspect who might have ties to the Chicago Liberation Army. Meanwhile, Alderman Gibbons takes matters into his own hands when an armed teenage robber threatens him, which triggers a reflection on his own youth and upbringing when he was more of an idealist.

Detective Wysocki and Evers encounter uncooperative locals while investigating the death of a teenager in Chinatown; Teresa's brother-in-law gets involved with a shady business deal; Liam goes deeper under cover.

When Superintendent Colvin calls upon Detectives Wysocki and Evers to locate a drug supplier who sent the son of an influential couple into a drug-induced coma, they uncover a more elaborate murder case. As the evidence stacks up, a downtown club where rich men and pretty women mix becomes the focal point of the case. Meanwhile, Teresa has her eyes set on securing funding to buy the department new radios.

The detective duo of Jarek Wysocki and Caleb Evers investigates an international drug dealer whose family is in jeopardy. FBI Division Chief Cuyler intervenes, complicating the high-profile case. While visiting grieving families with Alderman Gibbons, undercover cop Liam Hennessey becomes increasingly vulnerable when he feels the pain of victims. The family drama follows Jarek home when he visits his ex-wife, and wedding bells continue to ring for his fiancé.

During a heatwave, Wysocki and Evers investigate a homicide where the son actually saw his father's murder. In the meantime, Colvin gets a new driver. And Gibbons reaches out to Liam to help him with his constituents.

After five people are shot in Lincoln Park, the mayor blames Colvin for her lack of police work. Colvin puts Wysocki and Evers on the case to put her image to the public in a better light. Also, Isaac and Vonda are asked to look into an old domestic-abuse case.

While Teresa and Jarek set the stage for their case against Alderman Gibbons, their effort to clean up Chicago takes an unexpected turn when a deadlocked jury acquits a corrupt city official. Suspicious, the two mount an investigation, only to discover that jury tampering is just the tip of the iceberg.

Following a murder that appears to be a hate crime, Teresa risks tipping Gibbons off to her big-picture plan by boldly taking on the Chicago Police Department's corrupt "meritorious" promotion system. Meanwhile, Jarek is forced to face his own reality when Vonda receives an anonymous package that reveals more about the Wysocki family

The case against Alderman Gibbons escalates when Colvin, Wysocki and Evers scramble to locate a star witness. Meanwhile, as Liam rushes to collect more evidence, he is forced to take matters into his own hands.

FBI Special Agent Cuyler returns to see Superintendent Colvin; Jarek deals with family issues that have haunted him for years; and the case against Alderman Gibbons comes to a conclusion.