Following the death of a 10-year old girl the intelligence unit have one option to gain access to their suspect, go on the inside. Ruzek and Atwater act as inmates to work the case from the inside. Outside prison, Voight and Olinsky follow-up on a good lead to answer some questions about the shooting. Meanwhile, Burgess and Roman show three boys around district thinking they are part of the Police Explorers program, only to realize that's not quite the case.