Conan, Ayumi, Mitsuhiko, Genta, Ai, and Professor Agasa go to the Beika Department Store together. In the stairwell, they witness Hosokoshi, the head chef at the high-end restaurant on the top floor, being stabbed in the stomach by a disgruntled customer. Conan calls Genta, Mitsuhiko, and Ayumi to let them know the culprit escaped down a different stairway. The potential suspects are part-time worker Kamaya, housewife Mitsuko, and chef Miyanodai. Genta, Mitsuhiko, and Ayumi all saw the culprit, but each of their accounts is totally different from the others. Determining the culprit's identity will be rather difficult...