Karen Aldridge

At the site of a train accident, Peter Mills becomes deeply upset when he observes the dead body of a young victim. Unable to shake his emotional distress about the event, he questions his future as a firefighter. Dawson and Shay save a 6-year-old girl whose mother is abusing her – but their confrontation leads the woman to resort to dire actions. Meanwhile, Severide aggravates his injury while rescuing a heart attack victim and Shay sends Clarice, her married, pregnant ex-girlfriend, back home to her husband.

Frank faces public backlash after an officer's body camera malfunctions during an altercation with a civilian. Meanwhile, Danny and Maria struggle to protect an informant after the U.S. Marshall's Service decides not to put him in Witness Protection, and Erin investigates an old friend's daughter's claim of rape at a prestigious university.

Lt. Casey (Jesse Spencer) and Dawson (Monica Raymund) volunteer to help at a charity run at Chicago Medical when a massive explosion sends Chicago into chaos. With one of their own missing in the blast, the firehouse is tested like never before.

Dr. Rhodes (Colin Donnell) begins his fellowship in cardiothoracic surgery, but gets off on the wrong foot with his challenging new boss, Dr. Latham (guest star Ato Essandoh). Dr. Choi (Brian Tee) navigates life as the new chief resident and finds the road a bit rocky, while Dr. Charles (Oliver Platt) approaches Sarah (Rachel DiPillo) with an interesting opportunity that catches her off-guard. Elsewhere, April (Yaya DaCosta) works to come to terms with her recently discovered illness and Dr. Manning (Torrey DeVitto) deals with a complicated case involving a pregnant woman who was a victim in a high speed collision. Meanwhile, Dr. Halstead (Nick Gehlfuss) takes exception to the actions of fourth-year medical student Jeff Clarke (guest star Jeff Hephner), whose past history with Dr. Manning may be a factor. Sharon Goodwin (S. Epatha Merkerson) tries to pick up the pieces and move on with her life in the aftermath of Bert leaving. Marlyne Barrett also stars.

Dawson (Monica Raymund) starts her first day as a candidate and looks to find a balance with Lieutenant Casey (Jesse Spencer) inside the firehouse. Mills (Charlie Barnett) must come to terms with a future that doesn’t include the squad. Meanwhile, Severide (Taylor Kinney) confronts his demons in an unexpected way and the Molly’s crew has a date with the city inspector to make sure their food truck is up to code.