|The Sword Thief|
|Publication Date:||March 3, 2009|
|Preceded By:||One False Note|
|Followed By:||Beyond the Grave|
The group then goes to a train station according to a lead and Dan and Amy nearly get hit by a train. However, Alistair Oh pulls them into the room, saving them both. In this room, they find a haiku, which tells them to use geometry to find Hideyoshi's treasure. Later, they find some geometric shapes, but are chased by the Yakuza and are once again nearly killed. They are rescued by Nellie, who has struck a deal with, and is accompanied by, the Kabras. Ian gives Amy a small coin of importance to the search, after their hands brushed up against each other in the car, hoping that this token can gain Amy's trust.
They decode another message in the shapes, and some English letters. The message tells them to go to Korea. In Korea, everyone goes to Alistair's house. There, Alistair announces that he is tired so he'll take a nap, then they all can search for the Clue, Ian asks Amy if she wants to go in the maze with him, she refuses him since Alisair said no one should go wondering on the grounds, after a while, Ian comes out the maze screaming since Alistair's dog has bitten him on the bum, and ripped his trousers, he blushes in front of Amy, but quickly changes his attitude back in front of everyone else, since the screaming woke Alistair up, then he gives them a Clue to enter his secret library 'Why leave the factory when the workers are in their prime?', the Kabras automatically give up as they have no idea what time people work at, Amy is sure she has an idea, she figures out that 'why' sounds like 'y', when 'y' leave the factory, you get 'factor', then she notices the word 'prime', meaing 'prime factors', Dan quickly solves the puzzle, '5, 7, 11, 13', when multiplied together, they get 5005. They are then welcomed into the Oh sanctuary. There, they look up books about the Cahill family in Alistair's secret library, this fascinated Amy and Dan since they've never been told before about their family, while the Kabras find it rather boring since they've known everything since they've been children.
By reading one of them, Amy and Dan figure out that the secret of the 39 Clues is the secret to alchemy (the philosopher's stone), and also in one of the books they learn they have to go to a mountain called Pukhansan. While trying to find the mountain Ian offers a race between himself and Amy to a near-by boulder, to show she is strong, she accepts and beats Ian by a second, there they both stand on top of the boulder out of breath, Amy looks into Ian's eyes seeing him from a different point of view, her example is changing the angle of a painting and finally understanding the meaning, she feels embarrassed and thinks Ian is laughing at her, but realizes that his eyes are inviting her to laugh with him, her heart is racing as their faces are only inches apart, they soon get interrupted by Dan who calls them 'Mr and Mrs Kabra', causing Amy to blush. While on the boulder Amy spots the mountain and they all start to head to it, they find an entrance, and open it with the coin they have, it causes the cave to rumble and a boulder to nearly hit Amy, but Ian runs over to save her and lands on top of her, he places his hands to lock with hers and re-adjusts himself so his lips are brushing up against Amy's, the dust clears and everyone gets up, Ian realizes that instead of thinking about himself first, he thought about saving Amy first, which shocks and confuses him.
Inside, they find all of Hideyoshi's treasure, and the third Clue, Gold. The Kabras have a plan, but little do they know that Dan also has a plan. He discovers an anagram and says the next location is Lake Tash which he claims is located in Kyrgyzstan. The Kabras then betray them and seal them inside the cave, burying them alive. Dan begins to tell Alistair and Amy that he tricked the Kabras into going to a non-existent Lake Tash, but is interrupted by Amy. She realizes that they are surrounded by charcoal and gunpowder. Using the matches Dan took from the Thank You Very Much Hotel, they blow up the cave. Dan and Amy make it out, but Alistair appears to be crushed under falling rocks, and is presumed dead. The cops arrive and Dan and Amy tell them about Alistair. They then see Bae Oh talking to The Man in Black.
Dan and Amy find Nellie and Saladin in the parking lot of the park. On the way back to Alistair's house, Amy tells Nellie what happened. When they get back, Dan tells Amy that the actual word is Alkahest, not Lake Tash, which is the word for the philosopher's stone. Amy then figures out that it isn't Alkahest, but instead, Al Sakhet. 'Al' means 'of' and 'Sakhet' was an Egyptian goddess. They learn that their next location is Egypt. Nellie suggests that Dan and Amy both go take a shower. Dan walks into Alistair's bedroom, and finds a pair of filthy white gloves on the bed. He realizes that Alistair is alive. At first he is extremely happy, but realizes that he ditched them again. The book ends with Bae Oh, sitting in his office. He pages his secretary, but Alistair answers instead. Alistair threatens his uncle, and when Bae looks in his receiving room, no one is there.
In the audiobook, there is an audio extra about a conversation between Fiske Cahill and Bae Oh.
From pages 39 to 67 instead of the page number symbols have been written. The code to these symbols is given in the middle weapon surrounded by three tungten samurai swords. Like this we get "The competition is about hope.
A DEADLY ALLIANCE
There's only one rule in the race to find 39 Clues hidden around the world.TRUST NO ONE. But when the hunt leads fourteen-year-old Amy Cahill and her younger brother, Dan, to Japan, their only chance to find the third Clue seems to lie with their unreliable uncle, Alistair Oh. Will they be foolish enough to make an alliance? With a Clue on the line, Amy and Dan might not have a choice. But in the Cahill family, trusting your relatives can get you killed...."
- Fiske Cahill(The Man in Black)
The third book's have a red cover. In the front there are many swords and shurikens from Japan. Some Cahill's symbol can be found in the dangerous weapons. There are three pictures in the back cover: Amy and Dan; the first, and the second book of the series. The book's short description over here too.
The Sword Thief's cards.