When District 21 goes after a Colombian drug gang following a series of brutal slayings, an asset in the investigation emerges.
When the CBI investigates the murder of an antiques dealer found dead in a museum, the evidence indicates that the suspect may be a member of the team.
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.
Platt and Voight discuss their pasts; Jin uses a scapegoat when he is caught tinkering with Voight's computer; Lindsay realizes she needs to come clean.
Cmdr. Perry notifies the unit that Pulpo has been released to help with a case; Ruzek gets difficult news; when a bit of Lindsay's past resurfaces, Voight reminds her how far she's come.
