Secrets of Sea Pines by Robert J. Perreault

Famed explorer William Hilton landed ashore one night in 1662 and proceeded to bury a treasure on what is now Hilton Head Island. His death shortly thereafter and the subsequent loss of his Last Will and Testament turned what should have been his crowning achievement into a massive loss for his bloodline. To this day, the treasure has never been found. But that hasn't stopped others from seeking it. Charles Gramer grew up in nearby Hinesville, Georgia, devouring tales of adventure and swashbuckling mischief. On a train to Boston, he meets Mary Wheaton. Together, they stumble upon William Hilton's missing will and are immediately drawn into the mystery. Their newfound love creates a formidable partnership on a quest to find the treasure of a lifetime. However, what they get is far worse than they ever could have imagined.