Trixie Belden and the Mystery on Cobbett's Island (The Trixie Belden Series Book 13)

254 pp. "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?"