When the eccentric Blanche Porter reports that her beloved Mr. Cheeters has vanished, it isn"t your standard missing persons case. As Nancy Drew soon discovers, Mr. Cheeters, is a pet chimp. Or is he? Based on a preliminary investigation and information obtained from Blanche"s brother, Lawrence, the River Heights police dismiss the case as bogus - doubting that there ever was a Mr. Cheeters to begin with. But when Nancy Drew discovers there"s a missing diamond necklace as well - she"s on the case! Can Nancy, along with Bess and George, recover the great ape and the necklace, or has Blanche Porter made a monkey out of Nancy Drew? Ages 8 to 12.