“Who stole the emerald?” “Where did the gang plan to meet?” “In what city had the amnesia victim once worked?” Each question is scored to a degree of difficulty, with a perfect score of ten points per puzzle. And if you find you are stumped, you can turn to the back of the book, where the answers are printed (but upside-down, to deter you from giving up too easily). Don’t cheat: you’ll only spoil the fun.
In such puzzle-stories as “The Evidence on the Japanned Box,” “The Toledo Death Threat,” and “The Huppheimer Museum Robbery,” Wren and McKay sparked a craze for “ten-minute mysteries” that spread through the American pulp-detective magazines of the late 1920s. These are the originals – and perhaps the most perfect examples – of this venerable mystery puzzle genre to challenge the wits of armchair investigators.