The Detective Boys hear a rumor from a classmate about a warehouse with a treasure that can instantly appear and disappear. Before heading to the warehouse to investigate, the Detective Boys drop by Conan's house where they run into an unknown person unbeknownst to Conan. During the warehouse investigation, Conan notes there are fresh adult-sized footprints even though the warehouse has been locked up for years and that they lead up to an abacus with an odd number of beads. Conan decides to look through the warehouse by climbing a tree and sees a pile of treasure. The Detective Boys reenter the warehouse from the front entrance only to discover the warehouse it empty again. While Conan deduces that there might be a mechanism in the roof or in the floor, the Detective Boys prove him wrong declaring that the distance between the window and the roof is two meters from the outside and inside and that the markers they placed on the floors did not change.