A dog named John kills a college student, shocking the dog's owner and Conan as well! Conan's known the pooch forever, and if he doesn't get to the bottom of the attack, John will be put to sleep!

When Kogoro realizes that the death he's dealing with is not a suicide but a murder and that the perpetrator is one of his old friends, Conan tries to subtly give him hints to help him solve the case.