内容简介：
A summer vacation on a lake, two families and the adventure of a lifetime Two curious cousins exploring the deep woods see a strange site in the distance while at the top of a tree. They decide to investigate. Come along on a journey into a world of secrets and a 300-year-old mystery. Join Joe, Ronnie and their sisters as they unravel a puzzle full of clues, hidden caves, an old diary, possible treasure and much more. Along with the excitement is all the danger that an expedition like this can bring. What could be lurking in the caves? Will they solve the riddles, follow the clues and find treasure? Or will they get into trouble, lost, hurt, or worse? All the secrets will be revealed to you. Enjoy a "Stop and Think" section at the end of each chapter to spark your own imagination with "What do you think?" questions. A helpful vocabulary section is added so you'll understand everything. Read, imagine, learn and enjoy