Code Black takes place in the busiest, most notorious ER in the nation. At the heart of the ER is Dr. Rorish who is in the process of adopting a teenage girl named Ariel. Col. Willis focuses on field medicine with his ride-along partner, Rox. The ER and OR director is Dr. Campbell, a top-tier surgeon. The senior ER nurse Jesse Sallander guides third-year residents Dr. Angus Leighton and Dr. Mario Savetti and second-year residents Dr. Noa Kean and Dr. Elliot Dixon. Dr. Rollie Guthrie is the avuncular, wise grandfather to all.