Casey reconsiders his run for alderman after he's targeted by a propaganda campaign. The squad responds when a man is trapped inside of a burning car. Trudy's nerdy brother plans Mouch's bachelor party. Jimmy and Brett investigate a kidnapping on their own.

Severide and Cruz find a child's remains inside a chimney while investigating a possible carbon monoxide leak inside a home. In other events, Casey braces for the worst in his run for alderman while Alderman Becks continues to bad mouth him to the press.

The team responds to a building collapse that's trapped more than a dozen people. Dawson's quest to foster Louie is aided by a familiar face. Otis, who's on medical leave, meets his temporary replacement. Severide and Kidd continue to see each other. Casey is at odds with Antonio.

Boden and Jimmy are at odds. Kidd deals with her unstable ex. Dawson continues her quest to foster Louie. Casey's new political consultant urges him to think big. The team responds to a dangerous structure fire.

Severide and Stella search for Grant, who's AWOL from Chicago Med. Dawson questions her career path. Casey's relationship with his political consultant cools. Borrelli's anger at Boden over his brother's death boils over. Mouch and Brett partner on a new venture.

Casey and Dawson find themselves in the midst a potential political mess. Stella has to make a big decision about her ex-beau. The squad responds to an auto accident. Severide befriends a socialite. Brett and Mouch set aside their writing differences for the greater good.