Mathews plays Paul Farrell, who's going out with a young woman whose father is in an asylum, having killed the man who tried to rape her. He used an acetylene torch in the murder. Then Farrell falls for the girl's mother, and they hatch a plan to help her husband escape. Things go wrong.
Maniac was filmed in atmospheric black and white and written by Jimmy Sangster, who throws in any number of good twists. Even though I'm telling you right now that there's a twist ending, you might not figure it out while you watch the movie. Back in 1963, it was a real stunner.