Nancy, along with Bess and George, find the wreck of an old yacht with a safe inside full of jewellery worth a small fortune. Cousins of the Druthers, who are clients of Nancy's dad Carson Drew, owned the yacht. Their will leaves everything to Mr. Druthers, specifically excluding his spouse, (whom the cousins hated), but no one's seen him for ten years and the rumour is that Mrs. Druthers murdered him! Things take a surprising turn when suddenly Mr. Druthers reappears! But then Mrs. Druthers disappears! Join Nancy Drew as she solves the mystery of the fake heir!