Season 4 Episode 3
"I Walk Away"
Dawson uncovers a dangerous conspiracy; a drug dealer takes Brett and Chili hostage and Boden risks everything to clear 51's name.
As the internal investigation surrounding the team's actions in the drug house fire escalates, a crisis call to the same neighborhood prompts one witness to provide proof that exonerates 51.
At Arson, Dawson (Monica Raymund) finds evidence that Roger Maddox, a shady real estate developer, orchestrated the fire. When Boden (Eamonn Walker) secretly releases Maddox's connection to the press, he's ordered by his superiors to produce the evidence - or lose his job. When Boden and Dawson go to retrieve the files from Dawson's office, they find that all of the evidence has mysteriously vanished... and Dawson collapses in shock.
Severide’s (Taylor Kinney) new relationship shatters irrevocably when his girlfriend, an attorney, breaks Severide's trust and takes on Maddox as a client.
New candidate Jimmy Borrelli (Steven R. McQueen) is offered a transfer to a different house (arranged by his overprotective brother), but decides to stick it out with 51, the place Jimmy feels he belongs.