Three tiny, ancient beings Moss, Burnet and Cumulus, once revered as Guardians of the Wild World wake from winter hibernation in their beloved ash tree home. When it is destroyed, they set off on an adventure to find more of their kind, a journey which takes them first into the deep countryside and then the heart of a city. Helped along the way by birds and animals, the trio search for a way to survive and thrive in a precious yet disappearing world.