Kogoro and Conan are brought to an apartment to examine the death of a man named Yamamoto. It is presumed a suicide as evidence project he put a gun in his mouth and firing. His friend is suspected of murdering him as he left the crime scene without calling the police. When Kogoro is fed strawberries, Conan realizes who the murderer is. After investigating Yamamoto's dentist, Conan tranquilizes Kogoro and reveals the murderer to be Yamamoto's neighbor, Yumi Suzuki. Conan reveals that Yumi Yamamoto's dentist assistant and deduces Yumi entered Yamamoto's apartment and offered to treat him. When he opened his mouth, Yumi shot him with a gun. As evidence, Conan reveals that Yamamoto's coffee stirrer is acutally Yumi's dental mirror.

The Junior Detective Club were at the beach digging up clams. They encountered a college group of students on similar excursion. Later, one of the college boy was found dead from poisoning. Was it suicide, or murder?