The death of Judge Tommy Wells' (guest star John Pankow) daughter puts Intelligence on the track of a pill mill spreading into the suburbs of Chicago and the doctor enabling it. Meanwhile, Voight (Jason Beghe) discovers who's been leaking information from the 21st.
Halstead's (Jesse Lee Soffer) partying with Camila (guest star Anabelle Acosta) unintentionally puts him in the middle of a drug-related homicide. He's forced to choose between loyalty to his unit and his girl. Meanwhile, Voight (Jason Beghe) finally discovers the mole in his unit.