Conan and Ran pass by a dog park and befriend two couples whom each own a dogs; one is named Musashi and the other is named Coeur. Yoriko Nakatani, the neighbor of the owner of Musashi, the Tsutsumi couple, asks Kogoro to investigate the dog Musashi who acts aggressively to her. Conan and Ran disclose they believe she did something to upset the dog, causing her to leave. The next day, Nakatani's mother in law is seemingly killed by Musashi when his teeth marks are found on her throat. Conan investigates and is at a lost until Coeur finds a clay modeling of a dog's jaw and realizes how the murder is done. The police reveal Conan's deduction explaining Nakatani used the clay model to puncture the victim's throat. The blood on Musashi's mouth was from licking the wound in an attempt to ease the bleeding. Nakatani confesses and explains her mother in law was criticizing her on her visits and publicly exclaimed she wished she had chosen a better wife for her son.