Book Four in the exciting Doomsday Rats series. Berrin and the Rats return to battle against the evil of Malig tumora. On the streets of the city, the Gadges are on guard. there is no way to destroy the purple flowers which keep the grown-ups in Malig tumora's power. Or is there? Berrin has heard of a special moth that feeds on the purple flowers. It might be the weapon the Rats are looking for. the moth is said to survive on Mount Windenback, but no one has heard of such a place. Can Berrin and his team of Doomsday Rats find the precious moth before Malig tumora discovers it for himself and destroys their last hope?