Conan and his friends come to a lodge and fossil museum in Gunma to go on a fossil finding trip. Journalist Miyashita Umika also arrives at the lodge. She explains that she has come to write a story on the rare moon's droppings fossil that was discovered in the town. Museum owner Ogami and village mayor Nakatani are planning to make the fossil the town's village in order to promote it, but Umika mutters that she hopes it doesn't become a negative symbol. Later, Ogami is interrupted while trying to tell something to Umika, and his dead body is discovered in the bathroom...