Jackson Pauley and his nephew Zach, an Afghan war veteran and double-amputee, happen upon a buried vault, with ties to Black Caesar, a pirate who sailed the waters of the Florida Keys 300 years before. Seeing the vault and discovering a journal left behind by the person who built the vault, they are intrigued by the prospects of gold treasure. When men threaten Zach, and an archaeologist called in to investigate the vault goes missing, they decide to solve the mystery before anyone else gets hurt.