An injury sidelines Herrmann. Severide carries out a victims last wish after failing to save him. Casey wants to restart things with Hallie. The fire crew are having issues with a goat being on their insignia.
Casey is pressured into recanting a statement when he learns a drunk driver is the son of a veteran CPD detective. Severide learns the severity of his injuries. Mills wants out of the family business to pursue firefighting.
Boden faces backlash after his decision to pull his team from a burning warehouse. Voight steps up his threats against Casey. Severide suspects arson threats against an elderly lady. Leslie has an encounter with an old flame.
Kelly seeks help from his ex in acquiring painkillers. Herrmann gets stuck in a pyramid marketing scheme. The feud between Casey and Detective Voight becomes personal.
It's Thanksgiving and Boden order's a drug test for the 51, putting Severide in a tough position. Cruz's brother is injured in a gang shooting. Otis starts a podcast. Leslie's ex-girlfriend visits the firehouse.
Mills considers leaving the 51 after encountering the remains of a victim. Leslie is confronted by Clarice's husband. Severide develops an addiction to painkillers. Dawson suspects a mother poisoning her daughter.
An injury on the job forces Vargas to retire. Cruz seeks to pull his brother from a gang and the price is high. Severide starts a relationship with a woman he saved on a job.
The 51 crew is under investigation when a woman accuses the firemen of stealing a diamond necklace from her home. Cruz makes a risky move to pull Leon out of a gang. Things get serious with Kelly and Renée.