After a series of deadly ambushes, the team goes undercover to bring down a dangerous new drug dealer who is determined to push out the competition. Ruzek's informant proves to be a loose cannon that could upset the whole operation.

Ruzek's father, Bob, goes missing and the team races to find him before it's too late.

The shocking murder of a young pregnant woman leads the team on a desperate hunt for the killer, revealing something even darker than expected. Burgess has to make a tough decision about Makayla.

Halstead’s past resurfaces when a former Army colleague is implicated in a deadly blast. As the FBI launches an investigation into Roy’s disappearance, Upton feels the pressure of the secret she and Voight are sharing.

As the team investigates the stabbing of a father with two young daughters, they begin to suspect there is more to the story than meets the eye. The FBI investigation into Roy Walton’s death intensifies while Voight, Upton and Halstead feel the heat.

The team searches for a brutal killer with a signature modus operandi. Burgess and Ruzek double down in their fight to retain custody of Makayla.

Halstead takes a new recruit under his wing during an investigation. The dynamics are challenging, however, and questions arise over the recruit's complicated past.

The team investigates a string of brutal pharmacy robberies, and Halstead connects with one of the victims about their Army careers. Upton suspects there is more to the story and confides in Voight.

When actionable evidence finally surfaces against Sean O'Neal, Upton and the team work relentlessly to build a case in secret. They discover Sean is more elusive and dangerous than anticipated.

Atwater's worlds collide when a shooting at the building he owns in Burnside leaves a child dead. Atwater must confront his relationship with his father, Lew, as the brutal case forces them together.

Burgess works an extra shift at the 13th District and gets caught in the middle of a drive-by attack on refugees. The team works together to track down the shooter and uncover the true motive behind the attack.

As Atwater finds himself distracted by a past case, a CI from his past resurfaces with a tip on a string of armed robberies that are raising concerns.