While taking care of the rabbits at the animal shed, Conan, Haibara, Ayumi, Genta, and Mitsuhiko meet Teitan Elementary School graduates Murata Sho, Yanagimachi Gaku, and Ichihashi Seiko. They've been asked to dig up a time capsule while the rest of their class prepares for the class reunion. Akemi, the only person who knows the location of the buried time capsule, left behind a code, and the Detective Boys work with the graduates to find clues. But something strange happens during the search, and Conan believes someone may be interfering with their search for the time capsule.