Title: In Too Deep
Author: Jude Watson
Description: Fourteen-year-old Amy and her younger brother, Dan, head to the Land Down Under to discover what their own mother and father knew about the hunt for the 39 Clues. But following in their parents' footsteps bring up lost memories for Amy so awful that she can't share them...even with Dan. Haunted by the ghost of their past, chased by deadly competitors, Dan and Amy can't see who is an enemy and who is a friend. Their blindness leads to a terrible mistake...and death of a hidden ally.
In this book Amy and Dan are following their parents footsteps, which leads them to Australia. There, they meet their long lost cousin, Shep, have encounters with venomous snakes, spiders, and other cousins that want to win the hunt, too.
While this is all going on, memories are reappearing in Amy's mind about the night of the fire. Memories that make her feel guilty. Amy and Dan are also finding things about their au paire, Nellie, and are not sure if they should trust her.