A shocking ambush at a funeral leads the team into a heated investigation to find the shooters. Much to Atwater's surprise, he must rely on someone from his past to help in the investigation, dredging up old memories and revealing new truths.

Voight and the team help Assistant State's Attorney Nina Chapman pursue a drug runner who dodged prison years ago after Chapman's informant mysteriously disappeared. The investigation takes a turn when Voight uncovers a damaging secret from Chapman's past, threatening the investigation and Chapman's career.