Harry finds himself stuck in an extensive cave system filled with bats, treacherous drops, and hidden dangers. Luckily, Bear Grylls is on hand to guide him safely out! Bear Grylls Adventures series: Each book in the Bear Grylls Adventures series follows a different child at an outdoor activity camp. Once they are given the magical compass, they meet Bear in an amazing place and learn new skills and facts they can take back with them to their real life. There is so much information, and so much fun in these inspirational adventures. Paperback book. 128 Pages. Ages 7 to 10.