In Too Deep is the sixth book in The 39 Clues series. It was written by Jude Watson and released on November 3, 2009. The story is set in Australia and Indonesia.
14 year old Amy Cahill, her 11 year old brother Dan Cahill, and their au-pair Nellie Gomez head to Australia to discover what their mother and father knew about the clue hunt. There they meet their friendly surfer uncle Shep Trent, who helps them by transporting them where they need to go in his plane. Amy and Dan are on the trail of a mysterious criminal known only as Bob Troppo, and they also discover a secret expedition their parents went on around the world to look for clues. But following her parents' footsteps reminds Amy of the memories she had of the night her parents died...memories so painful she can't even bear to share them with Dan.
Page Numbers on the plane in the inside front cover page numbers (199, 26, 113, 74, 202, 81, 57, 176, 165) are switched for words:
Find the other Ekaterina scientist who came too close.