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 anaemia.
Carol receives a second chance at life when a new heart becomes available; Choi and Archer find themselves in hot water with an old patient; Halstead faces the consequences of the stolen trial medication.
Third-year med students begin their rotation in the ED, and Maggie keeps a careful eye on one of them; Manning, whose mom's health takes another decline, tries to cover up how she broke the rules to treat her.
Marcel worries he made a surgical error when a recent transplant patient comes in with complications; Carol is once again in distress; Halstead and Manning must take action to right their wrong.
An auto accident sends Goodwin into a spiral as she tries to help a young boy and his mother; Manning's secretive behaviour begins to draw the attention of Marcel and Halstead.