Fifteen old-fashioned but wonderfully challenging "detective puzzles," the unraveling of which requires your powers of observation and deduction.

In words, charts, and diagrams, you are placed at the crime scene and presented with facts established by the police. What do you observe? Which are the telltale clues? What do you deduce? And how will you answer the questions posed at the end of each problem: "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.