Dr. Cross, a psychiatrist, is treating a young woman, Janet Stewart, who is in a coma-state, brought on when she heard loud arguing, went to her window and saw a man strike his wife with a candlestick and kill her. As she comes out of her shock, she recognizes Dr. Cross as the killer. He takes her to his sanitarium and urged by his nurse/lover, Elaine Jordan, gives Janet an overdose of insulin. But he can’t bring himself to murder her in cold blood and asks Elaine to get the medicine to save her. She refuses, they argue, and he strangles her. He saves Janet’s life, but now faces two murder charges.
When Janet Stewart (Anabel Shaw) checks into a hotel to wait for her husband (Frank Latimore) to return to her from overseas duty at war she falls asleep and has disturbing dreams about him. As Janet awakens and looks out the window to see Dr. Cross (Vincent Price) in an adjoining building murder his wife, she goes into shock and will not respond when her husband arrives the next morning. When the hotel doctor calls in the psychiatrist on call Dr. Cross arrives, and seeing that Janet may be able to identify him sweeps her away to a private sanatorium he operates in the country. Eventually it becomes clear to the good doctor that in order to keep Janet quiet he must commit her to an insane asylum but when her husband begins to get suspicious and Janet begins to get her bearings Dr. Cross resorts to some tactic that may be fatal to his patients.