Amanda Marcheschi

Ripley and Charles treat a high-risk prisoner who may have dementia.

Olinsky's (Elias Koteas) daughter remains in critical condition following a massive fire leaving Intelligence on edge, but more determined than ever to track down the suspect. Voight (Jason Beghe) opens up the case, knowing that he has Stone (guest star Philip Winchester) and his team's full support in the investigation, and all of Firehouse 51 behind him to examine potential origins of the fire. Intelligence works to connect the dots between the building owner, those who were inside, and a string of potential suspects.

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.

Dr. Rhodes (Colin Donnell) and Dr. Choi (Brian Tee) disagree over the final decision made by a patient suffering from a life threatening heart condition. The pending lawsuit against Dr. Halstead (Nick Gehlfuss) continues to move forward and Sarah Reese (Rachel DiPillo) and Dr. Zanetti (guest star Julie Berman) scramble to save a patient with a misdiagnosed flesh eating bacterial disease. Elsewhere, Dr. Manning (Torrey DeVitto) treats a young girl diagnosed with a contagious bacteria, prompting her and Dr. Halstead to take action to avoid a major outbreak.

Dr. Halstead (Nick Gehlfuss) and Sharon Goodwin (S. Epatha Merkerson) deal with a husband intent on harvesting his recently deceased wife's eggs, but soon discover some vital information that surprises everyone. Dr. Charles (Oliver Platt) is brought in by Dr. Choi (Brian Tee) to aid a patient who is trying to remove his own arm from his body because he feels like it doesn't belong. Nurse Sexton (Yaya DaCosta) befriends the father of a child who is rushed into the hospital after swallowing magnets - a situation that Dr. Rhodes (Colin Donnell) and Dr. Manning (Torrey DeVitto) are concerned could present dangerous complications. Meanwhile, Sarah Reese (Rachel DiPillo) finally learns about where she will do her residency, but has last-minute second thoughts.