'This is a mystery readers' mystery novel, and a beauty' Anthony Boucher Walt McLean, the proprietor of Walt's Malt Shop, had been found dead by his niece. The attack did not appear to be motivated by robbery, but who would want to murder such a harmless and popular man? And what could the message in green really mean? A detective story delectably tied up with one of the greatest of detective classics-Agatha Christie's The ABC Murders.