The surprising arrival of a new fire truck brings both joy and chaos to members of Firehouse 51. Boden and Severide are asked to make peace with an old foe for the greater good. Brett receives family news while Foster plans a party with friends.

Firehouse 51 hosts a Halloween open house. Kidd and Severide help a young girl after she gets kicked out of her home.

Boden, Ritter, Herrmann and Kidd work together to take down a local politician responsible for a chemical fire. After his aunt's accident, Gallo worries about their future.