Dr. Rhodes begins his cardiothoracic surgery fellowship but gets off on the wrong foot with his new boss; Dr. Choi begins his life as chief resident; Sarah is caught off-guard by Dr. Charles; April tries to deal with her recently discovered illness.

Drs. Manning and Rhodes suspect that two separate cases involving sick babies may be connected; a homeless patient's upbeat disposition enlightens Drs. Halstead and Charles; Dr. Choi and a Navy corpsman deal with the toll of gang violence.

An Indonesian man who doesn't speak English arrives at the hospital with a mysterious illness; Dr. Halstead attends Maggie's family reunion; Dr. Rhodes accepts a complicated heart surgery without consulting Dr. Latham.

When several patients turn out to have the same rare infection, Dr. Charles' epidemiologist daughter comes in to consult; an elderly patient's son and young girlfriend disagree over his treatment; Dr. Reese tries to help a young drug addict.

A car crash at the Chicago Marathon leaves victims in critical condition; April and her medical resident brother must perform an intense operation in the field; an 8-year-old girl experiences sudden hearing loss; Dr. Choi treats a malnourished woman.

A young cancer patient struggles to tell her parents about her condition; Dr. Reese turns to Dr. Charles and Detective Lindsay for help with a troubled young man; a teen science geek and her friends impress Dr. Choi and Natalie.

Goodwin reunites with her childhood sweetheart; Dr. Halstead gets lured into a concierge doctor app idea; Dr. Rhodes treats a woman with a heart infection against the advice of Dr. Charles; a former patient of Reese's reaches out for help.

Halstead and Manning deal with two feuding brothers, one of which is in dire need of a kidney; a patient of Dr. Reese's comes to a crossroad; a 16-year-old with a genetic condition needs surgery, but the overprotective mother gets in the way.

Dr. Charles is tasked with evaluating a patient as a possible heart recipient; Jeff makes a confession to Dr. Manning; two MMA fighters arrive at Chicago Med in bad shape; Dr. Stohl returns from his sabbatical.

A heart transplant patient gets into a car accident, revealing issues that could complicate her surgery; the police officer who arrested Maggie is brought to Chicago Med with a serious injury.