As a big illegal job looms on the horizon, the FBI catches Harlee in the act and pits her against her own unit. As a newly turned informant, Harlee struggles to safeguard her on-the-job family and avoid arrest in order to stay with her daughter. Harlee engages in a perilous dance with her FBI handler, Special Agent Stahl (Warren Kole), who develops an unhealthy obsession with her. Meanwhile, Wozniak, acting as the unit's patriarch, begins an all-consuming hunt for the informant. Pressure mounts as the crew struggles to perform their brand of street justice under FBI watch.