Kogoro receives a letter from a mysterious person named Kurataya Komakichi claiming he wants to give him his family treasure, so he heads to Yamaguchi prefecture with Conan and Ran, but he's mistaken for a robber's accomplice and is arrested. Komakichi is the name of a robber who shot owner of Japanese-style cafe Takarada in the arm and stole millions of yen worth of Keicho gold coins. Kogoro is released after news site reporter Asuka clears up the misunderstanding. Kogoro, Conan, and Ran visit Hagi in their investigation into the case, but someone is trying to kill them.

Kogoro, Conan, and Ran arrive at a popular lakeside restaurant. On the table are five settings for dinners that have just been started, but the customers are missing. Later, Conan and friends find chef owner Kuchiishi bleeding from his head. When Kogoro asks about the missing customers, he points towards the back door. A note with the character for "curse" is posted on the door, and five sets of footsteps lead to the lake ten meters past it. Conan feels something is off about the crime scene and closes in on the truth behind the mysterious case...