Dr. Manning and Dr. Rhodes separately treat complicated cases involving sick babies, only to uncover that the two cases could actually be intertwined. Elsewhere, Dr. Halstead and Dr. Charles treat a homeless man with an upbeat disposition who sheds some valuable insight that prompts one of the doctors to learn a thing or two along the way. Dr. Choi has a Navy corpsman follow him for the day as they deal with the toll of gang violence in the city, while Dr. Reese tries to understand the delicate balance required in her new position.