It Was a Dark and Stormy Night: 9

In this ``pop-up mystery whodunit'' readers are invited to assemble clues and identify the thief who has heisted the Dudley Diamond during Lady Penelope Pig's dinner party. While lightning flashes ominously outside, Lady Penelope's guests--all sporting diamonds of their own--admire their hostess's prized gem. Although Inspector Derek Dog stands guard, even he can't prevent the lights from going out or the diamond from being swiped. Readers get first crack at solving the crime: the final spread reveals lift-up flaps depicting each character and possible motives, together with a small sealed envelope containing ``The Solution.'' Birkinshaw's playful illustrations feature appropriately gothic settings, and her comical cast of elegant animals is dressed to the nines. This clever book would work nearly as well without its movable parts; some of the constructions actually impede investigation by partially obstructing helpful clues. Ultimately, though, this is diverting fare for mystery lovers. Ages 6-9. (Oct.)