Agasa takes the Detective Boys on a camping trip when they run into Masumi Sera who eventually joins their camping trip. While Genta, Mitsuhiko, Ayumi, and Haibara collect firewood, they encounter a man burying a female corpse. After being discovered by the killer and being chased by him, they find refuge in a cabin in the woods. While in the cabin, they discover that it was actually the crime scene of the murder.