A car accident that occurs at the Chicago Marathon leaves a victim in critical condition and tests the mettle of Dr. Halstead, April and her fourth-year medical resident brother Noah, who must perform a difficult procedure in the field. A mother brings in her 8-year-old girl experiencing a sudden hearing loss and Dr. Manning is left to tend to the case, which takes a complicated turn. Dr. Choi deals with Olga, a woman who is malnourished, prompting him to bring in Dr. Charles to help assess the case. Meanwhile, Goodwin takes measures to get her personal life in order.

After witnessing a drive-by shooting and hitting her head, Dr. Manning struggles with the aftermath of a head injury. Complicating matters, she and Dr. Halstead deal with a teenage patient and her overbearing older husband, who might not be looking out for his young wife's best interests. Dr. Rhodes finds himself in a unique situation when he learns alarming information about the woman he went on a date with. Maggie is surprised to discover some unexpected things about the man she has been seeing. Dr. Charles is frustrated when Dr. Reese disobeys his orders and puts herself at risk.