Too many juvenile mysteries are based on a predictable core of a cliched incident and detail. This one is made complex simply by the jumbling together of several occurrences instead of one, but the ingredients are all tired and overworked. There is the theft of a rare animal. There is the attempt by a real estate profiteer to sabotage a plan to build an orphan's home. And there is the discovery of a long hidden sum of money stuck into a library book. Felix, a 12-year-old boy rescued from a reformatory, is blamed for everything until he and his best friend sort out all the answers. The interrelations of these and other minor incidents are cloudy and so are the motivations behind them.