Given the question: Build a movie plot around this: What doesnt Cliff believe? That Vince killed someone.
The answer is:
Vince Grayson (DeForest Kelley), a young man has a terrible nightmare in which he sees himself killing someone. When he awakens, Vince finds a coat button and a key and some blood on his own wrist indicating that his dream was no dream. Calling in sick, he goes to see his brother-in-law Detective Cliff Herlihy (Paul Kelly) and asks for help. Cliff doesn't believe that Vince has killed anyone, but agrees to investigate. When it happens that on an afternoon picnic Vince and his girlfriend Betty Winters (Kay Scott) and Cliff and his wife Lil (Ann Doran) discover the remote mansion from Vince's nightmare, and stumble upon a mirrored room just like the one in Vince's dream, Cliff confronts Vince accusing him of murder. When a local Detective Torrence (Jeff York) interrupts them and they learn more about the actual murder of Mrs. Belnap, the lady who lived in the mansion, Cliff tells Vince that he must turn himself into the police. The nerve-jangled Vince is driven to a suicide attempt, but Cliff, from his experience as a crime detective, deduces that his friend's nightmare was the handiwork of Lewis Belnap (Robert Emmett Keane), the mansion's owner, who is an expert hypnotist. Cliff convinces Vince to go to Belnap's mansion and confront him, while secretly taping the meeting for evidence. Belnap proves to be a slick character again hypnotizing Vince and getting him to try to kill himself.