In end of the film we learn that
In the opening situation of Alfred Hitchcock’s film Psycho, we’re at a hotel room where a man named Sam and a woman named Marian are seeing themselves privately. Marian seems like a very respectful woman, however, early in the film we see her steal $40,000 from her boss in the first opportunity she has. She takes the money and goes to California, to her boyfriend. On her way she stays at a motel where she meets Norman Bates who is a psycho killer, though we don’t know this until the end of the film. Norman has a mental problem where he tries to keep his mother alive by becoming his mother. At the end of the film we learn that in reality Norman killed his mother and tried to make her relive by bringing her corpse into the house and by demonstrating her jealous personality. Because of this he murders Marian, believing this is what his mother would do. He also murders the private detective that comes searching for her a week later. The climax of the film occurs when we find out that Norman in reality is a psycho killer. His problem gets resolved when he sees a psychiatrist and gets locked up.