When the kidnappers of Antonios son, Diego, demand the release of the drug lord, The Intelligence Unit uses all resources to find the boy. Later, the informant Antonio knows reveals the lead where Diego was held and arrested one of the kidnappers, but cant get information. With the blessing of Antonios wife, Laura, to do what is necessary, Voight and Antonio force out information that leads to Chicago Union Station. Detective Erin Lindsay finds Diego on the bus with the other kidnapper and goes onboard. After secretly trapping the kidnapper on board, the kidnapper tries to use the boy as leverage to get out. But Ruzek drives the other bus into the vehicle, forcing the kidnapper to let go of the boy Antonio kills the kidnapper as Erin saves Diego. The cops later attend to the funeral of Willhite.