Conan, Kogoro, and Ran are out to eat at a fancy restaurant with a stream that little boats carrying food sail to the rooms they are supposed to deliver the food to. After a while three men enter the restaurant, then after eating a woman screams and Kogoro, Conan, and Ran rush to the frightened women, pointing at a dead person. How was the murder done? And why was the victim in the room he wasn't supposed to be in?

Professor Agasa takes the Detective Boys to an abandoned house for a day of puzzle solving. But when the clues he hid are found broken, Conan realizes someone is living there.