When Conan and his friends hear that a UFO has been spotted at on the riverbed near Kometo Bridge, they go to observe the UFO. At the same time, Nagai, manager of Nagai Toys, brings debt collector Oshiro to Beika Bridge. From behind his back, Nagai throws a shining boomerang toy, and Oshiro leans across the bridge when he sees it. In the next moment, Nagai lifts Oshiro legs and drops him over the side. Later, Conan and his friends discover the boomerang toy and body, and Conan realizes the truth behind the UFO sighting...