Dr. Rhodes receives an alarming phone call that prompts him to rush out in the middle of an important surgery. Dr. Halstead comes to the aid of an FBI agent who is brought into the ER, but he suspects there is more to the story than he is being told. Dr. Manning and Dr. Choi find themselves on opposite sides of a major disagreement over doctor-patient confidentiality.

Dr. Manning's actions with a recent patient lead to serious repercussions. April and Noah disagree over a patient who is injured after a beating. Dr. Charles is visited by a childhood friend with a surprising revelation.

The crossover starts on Chicago Fire S08E04 Infection (I). It continues on Chicago PD S07E04 Infection, Part III (III).

Following the subway tunnel collapse, Ruzek and Kidd treat injured passengers and track down the missing offender. Archer and Frost perform a life-saving amputation.

The crossover starts on Chicago Fire S13E11 In the Trenches (I). It continues on Chicago P.D. S12E11 In the Trenches (III).