Shock Corridor (1963) - Samuel Fuller

Daily Globe newspaper reporter Johnny Barrett has just been institutionalized at a criminal psychiatric hospital as a sexual deviant, his sister Cathy charging him with attempted incest. What the institution psychiatrists don't know is that Johnny's deviance is all made up. Johnny wanted to be committed there to solve a crime that happened at the hospital, the murder of a patient named Sloan, the resulting story which Johnny believes will win him the Pulitzer Prize. The only people who know and support Johnny in this venture are Swanee, his managing editor, psychiatrist Dr. Fong, Swanee's friend who trained Johnny for a year for this job, and Cathy, who is really his girlfriend. Cathy in reality is scared for Johnny, fearing that Johnny cannot help but be affected by the battery of tests and to what he is being exposed on a 24/7 basis as a "crazy" person. Despite abhorring her own job as an exotic dancer/singer, which she does because as better paying than secretarial work it will get her and Johnny to their dream faster, she still believes what she does is more respectable than this undercover work. Three patients witnessed the murder, but in their mental states have not been able to provide any useful information to the police. Johnny believes as a fellow patient he can get one or a combination of the three to a lucid enough state for them to divulge the killer to him. The question becomes if he can discover the identity of the killer either before he is found out or the institution gets the better of him.