This series about the men and women of the Chicago Police Department';s District 21 who put it all on the line to serve and protect their community. Chicago Police Department';s newly-minted Intelligence Unit leads investigation into a string of murders possibly related to a Colombian drug gang, Desk Sergeant Trudy Platt has Officer Kim Burgess run an errand for her. Veteran undercover Officer Alvin Olinsky recruits Officer Adam Ruzek from the Police Academy, having worked with his father years before. They head to the address. Detectives Antonio Dawson and Julia Willhite head inside first, unaware of any threat.