Dink, Josh, and Ruth Rose investigate the disappearance of a valuable racehorse that Dink's uncle and his friend, Forest Evans, have just bought and entered in a race at Saratoga.
Dink and his friends meet an exchange student, Sammi, who is actually the prince of an island country, hiding from those enemies who have kidnapped his parents and who may be after him as well.
When Ruth Rose and her friends, vacationing in Florida, discover that her grandmother is about to invest in a project to recover sunken treasure, they stumble upon evidence that the entire plan may be a fraud.