The Intelligence Unit reel from losing one of their own while helping Antonio rescue his son from the Colombians.
Antonio's son was kidnapped and he has a feeling the Colombian drug gang is to blame. Pulpo, the Colombian gang leader, is being held in jail and suggests his release may trigger the release of Diego. During the investigation, Halstead learns some new information about Lindsay. Voight offers Antonio a new approach to get information on Diego's whereabouts.