Chicago Fire Episode 4.17 What Happened to Courtney

While responding to a potential carbon monoxide leak inside a home, Severide (Taylor Kinney) and Cruz (Joe Minoso) find the skeleton of a child inside a chimney. Severide is certain he knows the child's identity from a case he worked on years ago. He believes the young girl is Courtney Harris, a child who was declared missing and was presumed to have drowned in Lake Michigan. Working with a homicide detective, Severide begins his own personal crusade to solve the cold case, going so far as to reach out to the child's mother, for which he receives an admonition from Boden (Eamonn Walker). In the end, we discover that Severide was right all along - and he also solves the mystery behind the girl's death when the mother's brother accidentally reveals that the girl's neck had been snapped... a fact known only by a few. After a tense fistfight with the brother, Severide subdues the man, and the murderer is taken into custody.

Casey (Jesse Spencer) begins the last leg of his run for alderman, and all of Firehouse 51 pitches in to help land those final crucial votes. Alderman Becks (guest star Amanda Schultz) continues his smear campaign against Casey, and all seems lost when Becks arranges a last-minute debate that Casey will be unable to attend. But this setback turns into the one thing that puts Casey over the top, as he's photographed saving a man's life after a car accident, and the accompanying news story paints Casey as a hero. In the end, Casey wins, and Molly's throws the biggest celebration the bar has ever seen.