Free fall.
"The little ones are so fragile, aren't they?"
— Beatrice Cahill
Mission Hindenburg is the second book in the fourth series of The 39 Clues, Doublecross.
The Cahills are the world's most powerful family, but their strength is being tested. A sinister man calling himself The Outcast has targeted the family and set them an impossible test. He's recreating four of history's worst disasters and challenging the young Cahills to find and stop the tragedies before it's too late. Now, with one disaster behind them, siblings Dan and Amy Cahill and their friends have just days to discover what the Outcast's next move will be.
Their frantic search seems to be pointing toward a terrifying air disaster, the explosion of the Hindenburg airship. But no one travels by airship anymore - what do the Outcast's cryptic messages mean? The young Cahills must split up and take to the skies to try to find the answer... before their whole world comes crashing down.
Tropes:
- Anguished Declaration of Love: All Amy can muster before bracing herself from their impending demise by airship explosion is a hug to Dan, while saying "I love you, Dan". Luckily, the explosion turns out to be a sham.
- Badass Boast: Amy delivers a scathing one to the Outcast, after their failed mission to stop the recreation of the Hindenburg explosion."Listen to me, whoever you are. You are not fit to lead the Cahill family and I promise you this: we will find you, we will stop you, and we will win. You hear me? You can't treat us like pawns in your game anymore! We will end you, you monster! You hear me? We. Will. End. You!"
- The Bad Guy Wins: Although the young Cahills stopped the Titanic replica from sinking, they fail to stop the next recreation of the Hindenburg explosion, in the form of the Lucian airship. And the Outcast and Vikram benefit from this.
- Bound and Gagged: Cara falls victim to this by Eriele. Luckily, she gets out not long after.
- Broken Pedestal: Nellie is horrified when she discovers that Grace ordered Vladimir to kill her own husband, Nathaniel Hartford, after one too many suspicious activities from him. As a result, she burns the file containing the sent order at the first chance she gets, fearing that Amy and Dan would be devastated if they found out. However, she decides to personally inform them about this at the book's end.
- Cliffhanger Copout: The previous book ended with Jonah and Cara receiving cryptic texts from Sammy and Nellie, reading "IF WE DISAPPEAR ASK MABEL" and "SAVE MY KIDDOS" respectively, receiving no more response. The last time the readers saw Sammy and Nellie, the two were hiding in the Chens' home gym, hiding from Tiffany Chen and James Chen. As a result, it implied that the two were captured. However, this book ignores this cliffhanger, instead showing the two heading for Russia, unscathed.
- Death Seeker: Vladmir Antonovich Spasky is so remorseful about his past crimes that he feels he deserves to die alone on a hospital bed. When he sees Nellie, he believes she has been sent by Grace to kill him.
- He Knows Too Much: Beatrice is killed by the Outcast, as the former recognises the latter's identity.
- Hope Spot: Amy and Ian are initially relieved that the MIT airship was only sabotaged to lower before reaching the Karman Line, instead of exploding after surpassing it. However, Amy remembers that Eriele wanted Ian to be on this ship instead of the Lucian airship, which contained those who forced his father out of his position after his mother's loss in the Clue hunt. The Cahills can only look out their window as the Lucian airship ascends and eventually blows up.
- Interrupted Declaration of Love: Ian tries to confess his love to Cara, only for her to remind him to chase after a fleeing Eriele.
- Only in It for the Money: Eriele's motive in sabotaging the MIT airship.Katlyn: You'll pay for this!
Eriele: Wrong! I'll get paid for this, and handsomely! - Sudden Downer Ending: Unfortunately. Although the Cahill gang stop Eriele and discover that the MIT airship only had it's air supply sabotaged to prevent them from reaching the Karman Line, a shocking realisation hits them. This only leads them to helplessly see the Lucian airship reach the Karman Line and explode, killing 36 people, most of which were former Lucian leaders. Due to this, Vikram Kabra finally has the top Lucian position, while the Outcast is revealed to be looking for the Clues again. And although Nellie and Sammy escaped the Kremlin Lucian base unscathed, they still learned about Grace's darker side, especially her attempted assassination of her husband. This information is then begrudgingly passed on to Amy and Dan, who will undoubtedly question their grandmother's love.
- Wham Line:
- When Hamilton muses on not being able to reach his date due to the upcoming Hindenburg disaster recreation the Outcast will orchestrate:Jonah: I don't think your boyfriend would be impressed by a heap of burning metal.
- Vladimir begins to confess to Nellie and Sammy the murder of Grace's husband."For the one killing I was called to do and did not."
- After watching the news regarding the Lucian airship explosion, the Outcast opens a vault to take out a vial filled with a certain substance. What is it?
- To hammer home the aforementioned Vladimir quote, Nellie's last lines finally tell us the Outcast's real identity.
- When Hamilton muses on not being able to reach his date due to the upcoming Hindenburg disaster recreation the Outcast will orchestrate:
