With Voight suspended, Antonio takes charge of Intelligence to deal with overdoses of bad heroin, but Ruzek undermines his authority.

Intelligence hunts down the man responsible for the high-rise fire and the case gets personal for Halstead.

The team tries to rescue a teenage girl kidnapped by robbers; Voight and Platt attempt to clear Olinsky.

Burgess must choose between listening to Voight or potential new ally when a ride along goes sideways.

While undercover, Ruzek discovers his father is working for a suspected drug dealer and is forced to question if his dad is involved.

When an alderman’s wife is beaten to death, Brennan pressures Voight to close the case; Upton shares a dark time from her past to get a confession.

Voight tells Halstead to remain impartial when the leader of a local mosque becomes a suspect in the bombing of an Army recruitment center.

While CPD tries to take down a drug kingpin, Atwater faces a tough choice.

Antonio crosses a line that puts the entire team at risk.

Voight and Ruzek lock horns over how to handle the aftermath of the Antonio situation. Meanwhile, a series of violent carjackings turns deadly, and Ruzek must rely on a C.I. he grew up with to help solve the case.

An investigation into the death of a well known district attorney puts the Intelligence Division at odds with a mayoral candidate. Antonio returns to work but doesn’t trust his own judgment when an operation goes sideways.

While chasing a heroin supplier, CPD crosses paths with a convicted criminal recently released on a technicality. Halstead’s history with the man threatens the team’s ability to put him back in prison.

Atwater goes undercover to bring down the longtime head of a criminal enterprise and becomes entangled in a situation that tests his allegiances as well as his conscience.

Upton and Burgess find themselves in a difficult situation when Intelligence tracks a cache of cop killer machine guns to a local gun show in Wisconsin.

Using information from Cruz, Intelligence chases down the robbery crew that’s been using the lockbox key. Voight is under pressure to bring the crew to justice without tarnishing the reputation of a murdered firefighter.

Voight and the Intelligence Unit focus all their effort and resources into investigating the disappearance of an exotic dancer who served as a long-time criminal informant for their team.

A mayoral candidate is shot by an unidentified sniper, and CPD races to catch the shooter before he can take out his next target.

With the threat of a gang war looming, Voight and Ray Price must organize a peace summit to end the bloodshed before more innocent people get hurt. Burgess evaluates her future with Blair.

Intelligence’s investigation into the murder of Burgess’ boyfriend threatens to reveal a dark side she was unaware of. The real motivation for his murder uncovers a much more unsettling truth.

A violent crew is hitting pharmaceutical delivery trucks and stealing drugs, but their motivation is more complicated than just money. The case tests Upton and Ruzek’s relationship.

Antonio struggles with his guilty conscience as he tries to take down a major drug dealer. In order to protect his team, Voight takes a big shot at Kelton.