Katrielle receives an invitation, which is actually addressed to Professor Hershel Layton, from someone who calls himself Lord Adamas. The invitation is for a puzzle game at Richmond Court, the family castle of the recently passed Lord Maximilian Richmond. Katrielle decides to participate in her father's place.
When they arrive at the castle, they encounter the Seven Dragons of London, who also received an invitation. Then the voice of Lord Adamas sounds, saying that the winner of the game will receive the legendary Richmond Treasure, but that he will punish those who lose by publicly disclosing a big secret each of them carries.
They are heading into a room called the Hope room for the first puzzle. The description of the puzzle says: "Compare your numbers and solve the puzzle. Then your crime will be uncovered. The puzzle is to name that crime." The numbers indicate to notes with a number on it, each of the players received with the invitation. Katrielle deciphers this part of the puzzle, finding the word "mountain". She does not succeed, however, in naming the crime that is linked with it. But all of the Dragons seems to know the answer, to the annoyance of Katrielle who finds herself to be the only one who failed the puzzle.
For the next puzzle, they are heading into the second room called the Twinkling room. This time the puzzle says: "The puzzle is to locate the treasure. See how the treasure map glows." This leads to a box filled with different gemstones and shapes. The puzzle description continues with: "The puzzle is to pick the right one. The treasure's form reflects your number that day." Katrielle deciphers the right gem to be diamond, but does not figure out the right shape. Again, however, the Dragons seem to know it.
Back in the hall again, Katrielle deduces something happened in the Dragons past that is connected to the Richmond's. The right shape turned out to be a heptagon, but since there was no hint leading to it, Katrielle suspects the Seven Dragons to represent the "number that day". Phineas suggests to focus on the game for now and challenges Katrielle to figure her theory out by herself.
Katrielle then leaves the group to investigate the castle, for Lord Adamas said at the start that "all the hints are within the castle". Sherl is coming with her while Ernest stays behind, taking over Kat's place.
Ernest and the Dragons then head into the final room called the Treachery room. The puzzle says: "You stole the treasure and destroyed decency. Now you must face your crimes and etch his words into your hearts." With playing cards hanging all around the room, Ernest encodes the name "Miles", which the Dragons recognize as the name of Maximillian's grandson. Ernest is very confused how the Dragons seem to know so much about the Richmonds. Then Phineas decides to tell him something and reveals to know where the Richmond Fortune is.
Meanwhile, Katrielle finds a hidden niche behind a bookcase. Within it lies a deed for a plot of land at Mount Rosenberg which is signed by Maximillian. She deduces Mount Rosenberg should be the mountain referred to in the first puzzle. Then she calls Emiliana Perfetti and asks her to find out what happened at Mount Rosenberg ten years ago for she might solve the mystery of the Richmond Fortune.
Katrielle heads into a outstandingly clean boy's room. She wonders if one of the Richmond's relatives still lives in there, but then suddenly runs back towards the hall, seemingly startled by something she saw in that room. Katrielle explains that if Lord Adamas's goal is to revenge the Dragons, the game will not end with just the three puzzles.
In the Treachery room, Grant finds a card with on it the text: "Pull Lord Adamas's strings", referring to the ropes hanging at the ceiling. When they do, the strings fall out of the ceiling and the door got closed off. Then the ceiling starts moving downwards and the voice of Lord Adamas announces the start of the final game.
- Katrielle Layton
- Ernest Greeves
- Madame Gretchin Doublée
- Mayor Pipper Lowonida
- Phineas T. Barnone
- Liza Wight
- Grant Sloanes
- Cesar Chance
- Mustafa Fullhold
- Emiliana Perfetti
- Lord Adamas (voice only)
- Kat's failure to solve the puzzle
- The Seven Dragon's past
- Maximilian Richmond and the Dragons' relationship
- The deed to a mountain