Halstead returns to Med to help Goodwin with a secret investigation; Archer and Charles deal with twins who insist on being identical inside and out; Stevie and Dylan treat a young patient with sickle cell anemia.

Vanessa and Archer disagree on how to handle the victim of a motorcycle accident; Scott and Charles deal with a UNICEF negotiator with repressed trauma; Hammer and Halstead treat a high schooler with Addison's disease and a clingy mother.

Scott and Halstead deal with a dishonest patient whose lupus is in remission; a wealthy donor makes inappropriate advances toward Hammer; Vanessa, Marcel and Charles try to convince a young woman to have life-saving surgery.

Charles helps Scott with a longtime patient who was recently diagnosed with schizophrenia; Hammer, Maggie and Vanessa investigate the legitimacy of a patient's cancer diagnosis; Crockett is caught off guard; Will pitches a new medical technology.

Scott and Charles treat patients suffering from glass child syndrome and misdiagnosed ADHD; Crockett has to navigate hospital politics when he cares for a surgeon's daughter; Halstead and Hammer must lay egos aside to help save an elderly patient.

Hammer's worlds collide when her mother becomes her patient; Scott's history with the father of a patient interferes with his perception of a case; Crockett's allegiances are challenged when his patient's liver is a potential transplant match.

Marcel helps Blake replace a patient's liver; Taylor tries to prove herself; Halstead continues to pursue the truth about Cooper; Choi gets closer to returning to life in the ED.

Scott's loyalty to Med and the police department is challenged; the annual random drug testing puts a doctor's career in jeopardy; Choi tries a risky old-school method on a patient; Halstead helps Hammer search for her mother.

The outcome of Halstead's investigation weighs heavily on his mind as he works with Scott to save an infant; Hammer and Taylor both struggle to keep their secrets; Marcel and Blake work with Abrams to save a patient in need of a liver transplant.

In the aftermath of the Vas-COM scandal, Goodwin clashes with the hospital's new compliance officer; Marcel and Blake try to save a patient who has a son with severe autism; a patient's son lies to his father about his diagnosis.