While responding to a call of shots fired, Voight, Antonio, Halstead and the team come across a secret battered woman's shelter and discover the owner has been wounded and a resident of the shelter has been kidnapped. The team faces a challenge as the gunman is still at large and the identities of the women are kept confidential. Meanwhile, Burgess and Roman go undercover to track down a man robbing people by catfishing them on a dating app and Lindsay opens up to Halstead about her past