Recovering from amnesia, Dr. Arthur Calgary discovers that he alone could have provided an alibi in a scandalous murder trial. It ended in the conviction of Jacko Argyle. The victim was Jacko's own mother, and to make matters worse, he died in prison. But the young man's innocence means that someone else killed the Argyle matriarch, and would certainly kill again to remain in the shadows. Shaded in the moral ambiguity of murder, the provocative psychological puzzler of guilt, vengeance, and blood secrets is among Agatha Christie's personal favorites.