A handful of grain is found in the pocket of a murdered businessman!

Let us explain. Rex Fortescue, king of a financial empire, was sipping tea in his 'counting house' office when he suffered a sudden and agonising death. On later inspection, the pockets of the deceased were found to contain rye grain. What is that all about? It was a second incident, this time in the parlour at his home, which confirmed Jane Marple's suspicion that here she was looking at a case of crime by rhyme!