The latest Cam Jansen mystery, alas, is an open-and-shut case that makes only minimal use of her trademark photographic memory. (With a moment's thought, Cam's sidekick Eric could have solved it--and even the inattentive reader can hardly miss.) Cam, Eric, and Cam's scatty, loquacious, globe-girdling Aunt Molly (who supplies a smidgin of comic interest) are at the circus. Aunt Molly's wallet disappears. Other people's wallets disappear. A clown has bumped those people. Clown's themselves tan disappear, notes Cam, by shedding their disguises. At this point another clown misdirects her away from the Bumping Clown-who, it turns out, is his (female) accomplice. Nothing quite clicks (Cam even has to verify her own hunches here); but fans of the series will probably forgive it an occasional lapse.