Wrong Side of the Bars. Antonio believes a Colombian gang is involved in his son's kidnapping, Halstead learns new information about Lindsay, Voight offers Antonio a new way to get information about Diego's whereabouts.
Chin Check. Voight and the team check out a house that has been associated with a series of gangs, people from the past cause Halstead's temper to rise.
The district is in a state of change, Lindsay has moved to New York and the CPD is under scrutiny about the corrupt nature of its institution.
A series of deaths from radiation poisoning may be related to a deadly tome in the library.
The team is approached to exonerate a former frat boy who is charged with rape and murder; a turn in Davon Watkins' case forces Madeline to head back to Ohio; Bellows struggles with his campaign; Levi tries to find out more about Rosemary's past.