Ramon cannot believe what he has just found in an oyster he's brought up from an underwater cave where the Manta Diablo, the monster devilfish, lurks. Ramon is holding a pearl. Not just any pearl, but the most fabulous gem he or anyone else has ever seen.

But neither sixteen-year-old Ramon nor his father foresees the trouble that such a pearl can bring. It will be young Ramon who must stop the monster he has unleashed.