Recovering from amnesia, Dr. Arthur Calgary discovers that he alone could have provided an alibi in a scandalous murder trial. It ended in the convi, ction of Jacko Argyle. The victim was Jacko s own mother, and to make ma,tters 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 ambiguities of murder, this provocative psychological puzzler of guilt, vengeance, and blood secrets is among Agatha Christies personal favorites.