The Grumble Rumble Mumbler tells the age-old story of a child that can't get to sleep because of night noises. The reader is introduced to a cast of Maori monsters - not just the taniwha, but also the maero, taipa, and the ngarara - who help children see the funny side of the things that go bump in the night. It is a light hearted story, filled with love, and a funny twist at the end.