A familiar face steps in when an intelligence detective is abducted by a heroin kingpin in the season premiere.

The death of an eight-year-old boy sets off an investigation full of unlikely twists and turns.

A member of the team is held hostage by a man desperate to find his missing daughter.

Voight and Olinsky must revisit their past in order to stop an ex-con targeting cops for revenge.

Ruzek's future is on the line when an off-the-books undercover mission goes south. Then the discovery of a dead body jumpstarts an investigation into operatives who believe they are part of a covert CIA operation. Part 1 of 2.

Ruzek's future is on the line when an off-the-books undercover mission goes south. Then the discovery of a dead body jumpstarts an investigation into operatives who believe they are part of a covert CIA operation. Part 2 of 2.

The death of a teenaged boy exposes corruption behind the walls of an affluent school.

An investigation is launched when the team discovers the body of a government official.

The investigation into a dead body found at the bottom of Lake Michigan points to Voight's social circle.

An investigation becomes personal for Voight when an acquaintance from his past is caught putting others lives in danger. A doctor with personal connections to Voight (Jason Beghe) is under investigation when four of his patients are committed to Chicago Med after an overdose of chemo

The team investigates a string of violent home invasions to find the common threat.

Voight entrusts his former cellmate to help intelligence take down a cocaine kingpin.

The search for an officer attacking and robbing casino-goers exposes corruption inside the CPD.

After escaping from an upstate New York prison, Gregory Yates sets his sights on Chicago.

Burgess busts a mild-mannered college professor smuggling heroin to Canada.

The murder of a young boy rocks the community and becomes top priority for the CPD.

Intelligence becomes embroiled in a violent robbery case that put Halstead in the line of fire.

The team finds themselves looking into a kidnapping at a hidden shelter for women.

Intelligence attempts to expose a man kidnapping wayward young women.

An investigation is launched after an abandoned newborn baby is found by the lakefront.

Burgess is on trial after shooting an unidentified man who she believes shot her partner.

The team looks into a pyramid scheme operation that may be linked to a brutal murder.

A case turns personal for intelligence when Voight's son is connected to a murder investigation.