Trust No One is the fifth book in the second series of The 39 Clues, Cahills vs. Vespers.
When seven members of their family were kidnapped, thirteen-year-old Dan Cahill and his older sister, Amy, got ready for the fight of their lives. But the enemy, a terrifying group known as the Vespers, remained frustratingly elusive. They stayed in the shadows, picking off Cahills one by one.
And now the Vespers have landed their most serious blow yet - a blow that strikes at the very heart of the Cahill family. Because Amy and Dan discover that there's a Vesper mole in their innermost circle. Amy and Dan need to smoke out the traitor before the next hostage dies. They have just days to discover who has their back...and who wants to sink a knife into it.
Tropes:
- Cuteness Proximity: Sinead towards... her gun. That only makes her more dangerous when she fires it.
- Foreshadowing: The front cover code can be decrypted using A=1, B=2, C=3, etc. When solved, it reads "The father is dead". This is a hint towards The Reveal in the next book that Isabel Kabra was the one behind the AJT texts, posing as Dan's father so that she could get the Master Serum from him.
- Heroic Safe Mode: Amy goes into one near the third act, even referring to this "calmly observing instead of actually experiencing" side as "Safe Amy" (while the side that is actually living in the situation and experiencing it is referred to as "Scared Amy"). Last we see of her in the book, she literally takes off running away from the others after learning exactly what the Vespers plan to do, namely, creating a Doomsday Device and realizing that she has given them the final piece they needed to finish it. Now, it has fallen on her shoulders to stop it.
- Little Useless Gun: Sinead has (and uses) one, but contrary to what the trope title may make some assume, it's definitely not useless.
- Mixed Metaphor: Amy combines "late to the party" with "missing the boat completely", in what Ian refers to as "that appalling mixed metaphor."
- Rule of Symbolism: The blister on Amy's neck, incurred by a near-shot from Sinead's gun. When things get tense for her, she scratches it. After the final revelation where the Vesper's demands are revealed to be actually components for a Doomsday Device, Amy scratches it one more time... and it bursts, spilling blood and pus. This was all symbolic of Amy's worst fears regarding the Vespers finally coming to a head, as she is responsible for agreeing to do the deeds in the first place.
- Wham Episode: After The Reveal that Sinead is Vesper Three, Isabel Kabra returns with a vengeance. After they give their usual demand to Vesper One, he says they're done with giving him stuff, after one more: the Cahill Ring. Then we find out what the Vespers are using all of this stuff for: they're building a Doomsday Device. Finally, in order to combat them, Dan (seemingly) drinks the Master Serum.
- Wham Line: After Amy gives Gideon's ring to the Vespers as their last offer, Atticus does some research based on the ransoms they were repeatedly given throughout the second series. It turns out to be this:"The Vespers have been stealing plans and parts to make Archimedes’ doomsday device."
