For a class project, Conan Edogawa and his classmates needed to research a small business. The Detective Boys had to select a topic and opted to dive into the profession of Detective Kogorou Mouri. They could have easily interviewed Kogorou for the assignment but, driven by their curiosity, they decided to tail him for a full day. Although Conan and Ai Haibara were hesitant in the beginning, they eventually agreed to follow him. Unexpectedly, they stumbled upon a dangerous situation as Kogorou's current case took an unforeseen turn.