When the team finds the body of a widowed, single-mother in the trunk of her car, they are shocked to discover that the victim was in constant contact with Voight's (Jason Beghe) now-reformed son, Justin (guest star Josh Segarra). After Lindsay (Sophia Bush) and Voight find Justin has been attacked in the same manor and is critically injured, Antonio (Jon Seda) and the team know that Voight will be out for revenge. Meanwhile, Roman (Brian Geraghty) makes a difficult decision and Commander Crowley (guest star Barbara Eve Harris) has plans to make changes within the unit.
Intelligence investigates a gruesome case. Upon further examination, it appears the victim was wearing a CPD-issued wire at the time of his death. Meanwhile, Burgess (Marina Squerciati) meets her new partner, Julie Tay (guest star Li Jun Li), who came from one of the worst assignments in the city. Together they respond to their first call, and Tay shares details of her past. Additionally, Commander Crowley (guest star Barbara Eve Harris) confronts Lindsay (Sophia Bush) about why she and Voight (Jason Beghe) were at that location on the night that Intelligence pursued Justin's killer. Also starring Jon Seda, Jesse Lee Soffer, Patrick John Flueger, Elias Koteas, LaRoyce Hawkins and Amy Morton. Guest starring Jesse Spencer, Philip Winchester, Marlyne Barrett and Samuel Hunt.