Having narrowly escaped the Family back at the time machine facility, Layton and the rest of the group decides to meet Celeste at the Thames Arms.
The truth about London[edit]
Talk to Inspector Chelmey for Puzzle 117, which will net you a 
figurine sticker. Inspector Chelmey and Barton will also join your group to the Thames Arms. Move south and east to the outside of the Thames Arms, then talk to Future Luke to have him join your group. Enter the Thames Arms and talk to Celeste to finally get to the bottom of this mystery.
Layton will tell everyone that the London you're currently in is an elaborately designed set to fool everyone into thinking they've travelled 10 years into the future. The back room of the clock shop isn't a time machine, but an elevator into the ground, which means everyone here is currently underground. Dimitri wanted to complete his time machines, but simply kidnapping scientists to help him won't be very effective.
As a result, Dimitri set up this fake version of London so that the scientists would think they're really trapped in the future. This made the scientists work harder, as they all wanted to return to the present. Layton now asks the Barkeep for an explanation, as he was strangely calm when Layton entered the Thames Arms despite it being a Family hideout. Mystery 03 will be solved for real.
The Barkeep will remove his disguise, revealing himself to be Dimitri Allen. He claims that he booby-trapped the entire restaurant with explosives that will trigger if anyone except Demitri steps on one of the hidden panels in the floor. Dimitri will leave the building, but gives Layton a note to help him figure out the location of the sensors himself. Be prepared for the last puzzle battle in the game!
Puzzles Battle 03: Layton vs. Dimitri[edit]
Find all the sensors. The numbers written above and to the left of the map indicate the number of sensors present in each column and row, respectively. Derive the location of all sensors using the information provided, and mark them on your map.
A tragic tale[edit]
Having solved the puzzle, Layton notes that Dimitri might be giving them false information, as the location of the sensors, when the diagram is flipped upside-down, spells LIE in US-Version or INFINITY in EU-Version. Layton says that Dimitri didn't plant any bombs at all, and was just trying to distract them as he escapes. Cornered, Dimitri has no choice but to tell the truth. Talk to Dimitri.
Dimitri will reveal that he and Bill Hawks were good friends and colleagues 10 years ago, working in the same lab to invent a time machine. They created a prototype time machine, and Bill asked Claire to be the first human test subject. Dimitri objected having feelings for Claire himself and having discovered a flaw in the design, but the experiment went on.
Later, Dimitri discovered that Bill was trying to sell the power source behind the time machine to a large corporation, but had to demonstrate its viability as a power source. Bill rushed to begin the demonstration before the time machine was even finished, ending in a major explosion. Dimitri's life was ruined, but Bill still managed to sell the technology, using the money he gained to climb the political ladder and become the prime minister.
Dimitri kept trying to finish his time machine to save Claire and stop Bill, but Layton believes there is no use trying to change the past. However, he does state that Dimitri was used as a pawn by an even more devious villain. He reveals this mastermind to be "future" Luke, which he calls Clive.
A boy called Clive[edit]
Layton recalls that he witnessed a small child crying for his parents after the blast at the Polydimensional Institute. The child was named Clive, and his parents lived in the apartment block next to the institute, which was destroyed in the explosion. He was soon adopted by a kind and rich woman known as Constance Dove, who passed away just a few years later. Clive inherited Ms. Dove's fortune, but then worked at a newspaper company.
Clive found the man responsible for the explosion by using the newspaper company's resources. He concocted a plan to avenge his parents. First, he befriended Dimitri and helped him continue his research. Then, he created the fake London with his massive inheritance. Finally, he used his connections with the press to find scientists that would help Dimitri finish the time machine.
However, unbeknownst to Dimitri, Clive had secretly been assigning other scientists for his own project. When asked about it, Clive kidnaps Flora and departs to the lighthouse. Soon, the base of the lighthouse emerges from the river, revealing it to be a giant mechanical fortress! Can Layton stop Clive's insane plan before it's too late?