During summer vacation, Conan and the Junior Detective League head to the planetarium in Beika City for a free research project. The night before, a mysterious letter arrives for Conan. It is a challenge from an enigmatic detective, addressed "To the esteemed Kudo Shinichi." Who is this detective that knows Conan's true identity? The showdown among detectives, set against the backdrop of the planetarium, begins now! This work is produced as a planetarium edition of the "Detective Conan Plus" series. Episodes related to "astronomy and the cosmos" from Conan's long history will make an appearance. Unfolding under a sky full of stars, this spectacular Conan story is a work that can be enjoyed by everyone, from children to core fans.