While out on a bank run for his off-duty security job at the dispensary, Halstead and his co-workers find themselves under attack by a violent robbery crew which quickly becomes a full-scale shootout. Voight and Lindsay question the owner of the dispensary who mentions her business has received threats from local gangs upset she's cutting into their revenue. Meanwhile Roman, Burgess, Antonio, Halstead, Ruzek and Atwater follow-up on a lead and track down a potential suspect.

When a call comes in about a woman stabbing a man then fleeing the scene, Burgess and Lindsay go investigate and find a young woman with the weapon in her hand. The suspect turns out to be a victim and she tells Olinsky that she was held hostage for months and her kidnapper attempted to psychologically manipulate her into forgetting her identity while he physically abused her. The team sets out to find the woman's abductor before he can harm anyone else. Meanwhile, tensions are high at the station when Ruzek accuses Roman of having feelings for Burgess.