Holidaying in Jerusalem, Poirot overhears Raymond Boynton telling his sister, "You do see, don't you, that she's got to be killed?" Their stepmother, Mrs Boynton, is a sadistic tyrant who dominates her family. When she is found dead on a trip to Petra, Poirot proposes to solve the case in twenty-four hours, even though he has no way of knowing whether it was murder.
