The 39 Clues - Book 7: The Viper's Nest

The Viper's Nest is the seventh book in The 39 Clues series. It is written by Peter Lerangis and was released on February 2, 2010. The 39 Clues series is intended for children aged 8-12, and takes the form of a multimedia adventure story spanning 10 books. The stories focus on brother and sister, Amy and Dan Cahill, and their efforts to piece together clues left by the matriarch of the family, Grace Cahill, on her death.