Pryderi and his wife are hanging out with Rhiannon and her second husband, Manawydan, when suddenly all the people, domesticated animals, and signs of civilisation disappear from Dyfed. They proceed to do not very much about it for several years, until Manawydan gets cranky about his wheat disappearing and decides to take revenge on a mouse.

WARNING: Animal cruelty. Protagonist intends to (but does not actually) hang a mouse. Like, from a mini-gallows.