The Landons are in Virgin Islands National Park to help figure out what is destroying the coral reefs and causing the hawksbill sea turtle to disappear. Jack and Ashley become involved with Forrest Winthrop IV, the adopted son of a U.S. diplomat. Why is he so anxious to save an island woman named Cimmaron, and what secret do they share? The action builds to a dramatic climax at Jumbie Bay, where a full moon finally reveals all.