The culprit is Masuyo Mamiya. She is in reality a maid named Mutsumi Kishikawa, who killed the grand mistress and took over her identity to search the castle for the treasure. The Grand Mistress had figured out that the maid was searching for the treasure and wanted to fire her, so since their voices were similar, Mutsumi came up with the plan to take her place. But she feared that the daughter couldn't be fooled, so she killed her and the long-time servants by setting the tower on fire. The fire also provided with a way for her old identity to 'die' official. She killed the assistant to get rid of other treasure hunters.
But Mitsuhiko rescues Conan, Genta and Agasa by using the glasses to track them, instead of going into Mutsumi's trap. Then Agasa asks a friend, who is a specialist in plastic surgery, if he had heard of someone who had requested to look like an old woman and managed to get Mutsumi's real identity.
Conan shows her the way to the treasure, which, to Mutsumi's chok turns out to be the castle itself and a beautiful view. Mutsumi break down upon realizing that she paid too high a price for nothing by killing people and change her appearance into a old woman.
People
Katsuo Tabata
41 years old
Mamiya family gardener
Mitsuru Mamiya
49 years old
Husband of the eldest Mamiya daughter (Married into the family)
Takahito Mamiya
25 years old
Son of the eldest Mamiya daughter
Masuyo Mamiya
83 years old
Head of the Mamiya family
Major events
Ayumi admits to Ai that she feels very affectionate to Conan, saving some bread for him because she thinks that if he is lost, he is also very hungry.
This is Shinichi's first ever murder case. His incredible deduction skills completely overwhelm and impress Inspector Megure. This is also very early in Takagi's career as a member of Megure's police force.
Ran and Shinichi's budding feelings for each other are briefly explored.
The whole episode takes place before the actual show. This airplane trip is what leads into Shinichi Kudo's New York Case.
