In a dark room, a thief is frantically looking through an office for something. When he finds it, he smiles and cut opens a bear. The next day, the Detective Boys went to Kumamoto with Ran and Kogoro for a sightseeing trip. Kumamoto is known as the capital of water for its amazing water sources, but is also known as the country of fire for its volcanoes.

The Detective Boys are playing soccer when they meet a cat who regularly comes to Café Poirot for food. Wanting to see where the cat goes, they follow the cat into a refrigerated delivery truck. But they also discover a body! As they hide in the truck, they learn the drivers killed the man and are doing their route to establish an alibi.