While serving a sentence for killing his foster mother -- a crime he insisted he didn't commit -- Jacko Argyle dies in prison. Two years later, the man who could have supported Jacko's alibi suddenly turns up. Recovering from amnesia, Dr. Arthur Calgary discovers what happened in his mental absence -- and that he alone could have provided an alibi in a scandalous murder trial that ended in the conviction of Jacko Argyle for killing his mother. But the young man's innocence means that someone else killed the Argyle matriarch, and that person would certainly kill again to remain in the shadows.