Kidd takes the lieutenant's exam and is nervous how she did.
Boden announces at the end of the episode she passed.
Severide floats the idea of proposing to Kidd by Casey. He also encourages Casey to tell Brett how he feels.
Firehouse 51 responds to a fire at a pet food facility, and Casey and Severide work with the owner to identify the person responsible for illegally dumping sulfuric acid on a nearby vacant lot, which started the fire.
Casey and Severide track the source back to the owner of a gardening company and hatch a plan to catch the guy in the act.
The plan doesn't go according to plan, and Casey, Severide, and Herrmann have to pull the husband off the owner.
Casey and Severide then enter the gardening company facility and find the evidence they need, linking the owner to the illegal dumping.
Brett's apartment is being fumigated and brings Veronicat to work for the day.
At the same times, Gallo, Ritter, and Mouch help with the firehouse's annual garage sale, and Mouch accidentally sells Veronicat.
Brett is elated her demon cat is gone.
Mouch also learns he will be awarded the firefighter's medal of valor.