The Unholy Four (1954)

Philip Vickers mysteriously reappears to his wife and friends during a party at her upscale country estate after an absence of four years. He had been presumed dead after he disappeared on a fishing trip in Portugal with three friends. He was knocked unconscious and pushed overboard by an unknown assailant. In the interim, he had suffered from amnesia but now has regained his faculties. All the potential suspects, including his wife, are at the party. When one of them is killed, the police are called in, and suspicion for the crime falls on the vengeful Vickers.