Borribles are small, looking like children apart from the fact that they have pointed ears, but they may be hundreds of years old, for they can live forever, unless they are caught and get their ears clipped. If that happens they will turn into regular children and will be doomed into growing up into boring, adventureless adults.
The trilogy begins with the story of the great Rumble Hunt, where nine Borribles go on a mission to stop the Rumbles invading their manors. Eight are nameless adventurerers out to earn a name, while the ninth, Knocker goes as their historian, but has another aim as well. He wants to get a second name, for all Borribles must earn their names, and no Borrible can go adventuring once he has a name. This may be his chance.