Get ready for fun, adventure, and intrigue in the iconic mystery series starring the beloved teenage girl detective, Trixie Belden! When the Bob-Whites arrive on Cobbett’s Island for vacation, Trixie finds a mysterious letter. Many years ago, a fortune was hidden. But the clues in the letter are hard for Trixie to understand. What does “start sailing” mean? Is this a treasure hunt on land . . . or on sea?

While on a trip to St. Louis, fourteen-year-old Trixie Belden discovers some mysterious papers in her hotel room and soon realizes that she and her friends are being followed as they cruise in a towboat down the Mississippi River.

Trixie Belden and the other members of the Bob-White club try to learn the reason for the sudden appearance of Diana Lynch's long-lost uncle.