Cam Jansen, the fifth-grader with the photographic memory, clicks her way through another simple, briskly unraveled mystery. Once more, as in Cam Jansen and the Mystery of the Stolen Diamonds (1980), Cam and her friend Eric are on hand when a robber runs from the scene of his crime. This time Cam has made a real box camera for the science fair; and she has just taken Eric's picture when the young man, emerging from a coin shop, runs by and jostles the camera from her hands. This time Eric grabs the camera as it falls, and though it is snatched from the school science-fair display, Cam doesn't need its evidence to catch the thief. Using her mental camera, she describes the young man to the store owner, who didn't even know he was robbed, and then, outguessing the police, shows them where the culprit has hidden the stolen coins. Cam doesn't win the science-fair prize, but that's okay too.