When a high school student becomes an innocent victim of a gang retribution incident, a very determined Lt. Casey tries all means necessary to resolve the issue. Severide lends a hand to Detective Holloway, who is working a dangerous undercover investigation, and watches over her 9-year-old son at the firehouse. Brett and Jimmie are called to aid a woman who takes a fond liking to Jimmy. Meanwhile, Otis makes a surprising discovery that leaves him very concerned and Herrmann goes toe-to-toe with Stella to claim bragging rights over who can best run a bar.