A young scientist fakes insanity so he can kill the husband of the woman he loves.

Jim Grayam, a research analyst in California, rescues his boss's wife, Lorrie Benson, from a car stalled on a railroad track. He discovers that the accident was really a suicide attempt made because Cort Benson is so cruel to her. Lorrie, afraid to leave her husband out of concern for their child, starts an affair with Jim. Cort discovers the affair and also learns that Jim was once treated for mental illness. Cort attempts to avenge himself on Jim by framing him on charges made by Angie DeWitt, but police Sergeant Dawes spoils this attempt. Cort next takes advantage of Jim's mental history to convince others that Jim is going mad. Jim and Lorrie grow closer and evolve a plan whereby Jim will study the symptoms of mental illness and then pretend to be insane, finally murdering Cort. He will be able to plead not guilty at his trial by reason of insanity and after acquittal will be reunited with Lorrie. The plan works up to a point; Dr. Larstadt agrees that Jim is insane, but after the trial she refuses to release him from institutional care. Jim cannot adjust to the asylum, and when he finds out that Lorrie has another boyfriend, he goes completely insane.