S3, E15: While working at a sobriety checkpoint, Burgess (Marina Squerciati) finds a duffel bag full of heroin in the truck of a respected college professor who claims to know nothing about how the drugs ended up there. Voight (Jason Beghe) decides to hold off on charging the unlikely suspect and Olinksy (Elias Koteas) and Antonio (Jon Seda) follow up on a lead to see who is behind the drug smuggling. At District, Roman (Brian Geraghty) expresses his desires to become a Field Training Office to Platt (Amy Morton), and Mouse (guest star Samuel Hunt) sets Halstead (Jesse Lee Soffer) up with an off-duty security job working for the attractive owner of a medical marijuana clinic.