A Spanish treasure ship is driven by a hurricane onto the rocky shoreline of Elbow Cay in September of 1566. Few of the crew survive, but they manage to salvage most of the treasure and bury it on the island, leaving a clue to its location in a chest placed in the boughs of a young mangrove tree. Four hundred forty years later, Jesse McDermitt and his friends solve the riddle that was hidden inside a chest found encased in the now-ancient mangrove.

When the head of the Miami-based Croatian mob learns about the treasure he goes to great lengths and expense, in an attempt to relieve Jesse and his friends of the riches. A demented, hyper-sexed island woman also wants it for her own, as does a hot-shot Miami attorney and his son, who is married to Jesse's estranged daughter.

As the body count grows, will the crew of Gaspar's Revenge find the treasure or become one of the island's statistics?