Susan's investigation then reveals the mastermind behind all of it - Dr. George Harris (Richard Widmark), Chief of Surgery, who she has been confiding in all along. Dr. Harris tries to stop Susan from exposing the truth, and attempts to render her brain dead with carbon monoxide in operating room eight, under the pretext of performing an appendectomy. However, Mark, now having realized the truth as well, manages to find and disconnect the pipe before it can poison Susan. The movie ends with Susan awake, being wheeled out of the operating room holding Mark's hand. Meanwhile, Dr. Harris stands defeated in the operating room, as two police officers wait outside to arrest him.
