Several patients are discovered to have the same rare infection, prompting Dr. Charles' daughter Robyn, an epidemiologist, to be brought in to find the common link. Dr. Choi and Dr. Rhodes work on an elderly man who is discovered to be very ill, but a conflict in how to best treat him develops between his son and his young girlfriend. Meanwhile, Dr. Reese tries to help a young drug addict and Maggie tends to a patient who is dear to her heart.

Dr. Manning tends to a young cancer patient and struggles to inform the parents of her dire condition. Elsewhere, Dr. Reese gets contacted by Danny, the troubled young man, and turns to Dr. Charles and Det. Lindsay for help in resolving a difficult situation. Goodwin and Maggie do their best to clear the logjam in the hospital and Dr. Rhodes fine-tunes his instincts after both Dr. Latham and Dr. Halstead pick up on things he doesn't. Meanwhile, a teenage science geek and her friends impress Dr. Choi and Natalie with their bio-engineering lab.