After a slew of brutal slayings, District 21, led by Sergeant Hank Voight go after a Columbian drug cartel cleaning house in Chicago. They discover D’Anthony, who proves to be an asset in the investigation. At the District, complicated histories and unit rivalries surface which could end up costing them one of their own. Meanwhile, Rookie Adam Ruzek is pulled from the police academy by Olinski to join the team.
