There's a violent quilt in Alex's bedroom and a mystery visitor has been in the Takeshitas' house, drinking tea out of their best cups. And then Kazu is stolen for the second time. Miku, Cait, Alex and the little Filth Licker must solve the trail of clues leading them to an invisible house full of demons, the home of Nurarihyon, the Master of the Demons. But is he really the evil one they have come to fight, or is someone or something else controlling him. With only a bag of fish-heads to protect them, the children and the Filth Licker meet their final challenge in the frozen palace of the Yuki-Onna, the Snow Woman, where they find Kazu imprisoned in a cage of ice, and where the Snow Woman is determined to destroy them!