The Alligator People (1959)

Under therapeutic hypnosis, a seemingly well-adjusted young woman tells a fantastic story, verified by lie detector, of her forgotten marriage to a man who disappeared on the day of their honeymoon, and of her search for him which takes her to a lonely mansion in a remote section of swampland tenanted by snakes, alligators, a drunken one-armed lout, a mysterious doctor, and a cold-hearted elderly woman who lives alone in a brooding manse.