Island of Dangerous Dreams — Joan Lowery Nixon

Andrea didn't want to accompany her aunt and a group of privileged people on a boat trip to the Bahamas to look at a valuable artifact. But she's stuck there now, and angry when she realizes that this is a stolen artifact. All the adults want to own it, but Andrea knows it should be retumed to the Peruvian government. Then the object disappears... and someone is found murdered. Who will be next?