Another thrilling summer has begun in the Florida Keys for seventeen year old CJ Jansen and sixteen year old Skye Somers and their two friends, Flapper the pelican and Squeaky the dolphin, with whom Skye has the amazing ability to communicate. Diving around the Marquesas Keys, they discover a large gold chain that has a beautiful emerald surrounded by diamonds attached. The teens are elated about their find until a note on Poppy's door warns them to stay away from the Marquesas. Skye, undaunted by the note, learns from Squeaky that more gold can be found in deeper water. Excitement, frightening threats, underwater creatures and death follows the teens as their old friend Cap agrees to take them diving out in deeper water in the Money II. Unknown to all of them, something huge and frightening lurks in the waters where they dive, and one of them will pay the price for the Marquesas gold.