Accused of bludgeoning his mother to death with a poker, Jacko Argyle had maintained his innocence throughout his trial, claiming he was hitchhiking on the night of the murder and had been picked up by a middle-aged man in a dark car. The police were never able to locate this mystery man--until he shows up a year later. But Dr. Arthur Calgary arrives too late to substantiate Jacko's alibi. For after serving just six months of his life sentence, Jacko dies behind bars following a bout of pneumonia.