| Spoiler warning!|
This article contains plot details about In Too Deep.
|In Too Deep|
|Main Setting(s)||Various locations in Australia and Indonesia|
|Publication date||November 3, 2009|
| Preceded by|
The Black Circle
| Followed by|
The Viper's Nest
In Too Deep is the sixth book in The 39 Clues.
In Too Deep was written by Jude Watson, a Madrigal undercover as an Ekaterina.
In Too Deep
Fourteen-year-old Amy Cahill 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 brings up lost memories for Amy so awful that she can't share them...even with Dan. Haunted by the ghosts 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 the death of a hidden ally.
The beginning of the book introduces the setting as Sydney, Austraila. Amy and Dan have arrived to meet their Uncle Shep in an attempt to figure out why their parents visited before they died. On the way, they meet Isabel Kabra, disguised as an old woman who steals Amy's necklace that once belong to Grace. They give up, but end up inside a museum where Amy does get to talk to Isabel Kabra one on one, and they figure out a lead: Bob Troppo.
Irina realizes that she does not wish to continue working for Isabel anymore, who wants to take out the Cahill children. She refuses to let them die while Isabel is in command, based on the fact that her child died because Irina followed Isabel's command. Irina tries to shed light on the night of Amy and Dan's parent's death by telling Amy that the fire was not an accident, but a murder caused by Isabel Kabra.
Later on, Isabel manages to tell Amy the same thing, only that the fire was caused by Irina. The novel consists of Amy trying to figure out exactly who caused the fire while simutaneously finding a clue.