The Ghost of the Rock — S.K. Epperson

A search for diamonds on an island with a history of murder and insanity leads Sutton De Berg and her adopted older brother Gerard Brach to remember feelings they suppressed years ago. But Sutton's father, the wealthy Edward De Berg, and her French husband, Paul Dubois, have nefarious plans for any treasures found on the island, and the ghosts that haunt the atoll will wreak havoc and take lives before its deeper truth is revealed, more dangerous than any of them ever imagined.