Bad heroin is causing overdoses in Chicago, and Intelligence is a man down with Voight suspended. Antonio takes charge, but Ruzek undermines his authority.

Politics get in the way as the team tries to rescue a teenage girl kidnapped by a robbery crew. Voight and Platt try to exonerate Olinsky.

A ride along goes sideways, and Burgess is faced with a difficult choice: follow the advice of Voight, or a potential new ally.

The wife of an alderman is beaten to death, and Voight is under pressure from First Deputy Superintendent Brennan to close the case. To elicit a confession, Upton tells a dark story about her childhood.

In an attempt to dig himself out of a hole and save someone close to him, Antonio crosses a line that puts the entire team at risk.

Intelligence crosses with a mayoral candidate while investigating the fatal shooting of a well-known defense attorney. Antonio returns to work but questions his own judgment when an operation goes sideways.

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.

With Kelton’s election all but assured, Voight and his team must go off book in a last-ditch effort to save Intelligence from getting axed.

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.