Kantarou is called in by an old teacher to help in an investigating an island where people have been getting killed.  Joining them is another of Kantarou acquaintances - a man who believes in science and not in monsters.  Kantarou and Haruka discover a possessed giant rat creature and banish the spirits.  At the same time, the scientist drains the lake into the caverns below and thinks that he's solved the rat problem.