Kogoro Mori finds himself in deep trouble when a man is murdered shortly after visiting his detective agency. All the evidence points to Kogoro as the prime suspect. Convinced of his own innocence but unable to prove it through the usual channels, Kogoro escapes custody and becomes a fugitive. While on the run, he uses his deductive skills—and his old network—to investigate the murder on his own. Meanwhile, Conan secretly assists him from the shadows, doubting Kogoro's guilt and determined to uncover the truth. As Kogoro follows the trail of clues, he discovers the real motive and perpetrator behind the crime, leading to a tense confrontation. In the end, his name is cleared, but not without pushing the boundaries of the law and public trust. This rare case places Kogoro not in the role of detective, but as the suspect—putting his reputation, freedom, and friendships to the test.

Conan and his friends were playing Frisbee at the park, when a dog named Matsunosuke launched off of Conan's head and caught the Frisbee. Matsunosuke's owner, Kanae Asakawa, apologized and took Conan's jacket in order to get it cleaned after Matsunosuke left dirt all over it. The next day when Conan and the Detective Boys arrived at her house to get the jacket they met Kanae's friend Tomoko and see Matsunosuke in his dog house, asleep.