Trust no one.
"You are afraid of everything except what you should fear."
— Irina Spasky
In Too Deep is the sixth book in the first series of The 39 Clues.
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 in the hunt for the 39 Clues. But following in their parents' footsteps brings up lost memories so awful that she can't even 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.
Tropes:
- Bait-and-Switch: As Amy, Dan and Nellie are staying at their uncle Shep's house, Shep suddenly and quickly tells them to get in his car, seemingly confirming that either one of the other Clue hunting teams have discovered the trio's location, necessitating a quick escape. However, he only said this because he didn't want to miss the opportunistic waves at a nearby beach.
- Bittersweet Ending: Irina dies trying to save Amy, Dan and Alistair, while the aforementioned three are still stranded on the Indonesian island, awaiting rescue from Nellie. However, Dan and Amy have uncovered the Clue without letting Alistair know, Amy has finally mended her bridges with Dan, and the two have finally found a reason to keep on participating in the Clue hunt: not only for their parents, but for those who lost their lives due to their hunt.
- Call-Back: Amy's alliance with Hamilton comes back in a helpful way, as he ends up saving her from almost being eaten by sharks.
- Chekhov's Skill: Irina's Agent card, contained with this book, has a picture of a pole-vaulting gold medal at the back, indicating that she is highly skilled at this sport. During the house fire in Indonesia, as Amy, Dan and Alistair are trapped at the house's top, Irina arrives on the scene and uses a long bamboo stick to vault herself up there, giving the three something to slide down and escape from.
- Heroic Sacrifice: Irina helps Amy, Dan and Alistair escape the burning house via a bamboo stick and a handy Chekhov's Skill of pole-vaulting. However, there is too little time for her to escape as well, with the flames weakening the bamboo stick's strength. Therefore, she perishes in the flames.
- The Reveal: Irina secretly tells Amy that Isabel Kabra caused the fire that killed Amy's and Dan's parents.
- Sacrificial Lion: Irina becomes the first major casualty of the Clue hunt.
- Sarcastic Confession: When Uncle Shep asks what Amy and Dan are trying to do and why people are trying to kill them, Dan tells him the truth. Of course, Shep doesn't believe him, especially because Dan had made up several false, equally ridiculous stories before.
- What the Hell, Hero?: Dan calls out Amy for her keeping secrets about their parents' deaths.
