When a tree cries out in pain, some unexpected heroes come to the rescue. Nema and her gang of young nematodes (tiny worms) embark on a dangerous journey underground. The Xenos, a group of wise but deadly bacteria, hitch a ride. The story of how they help the tree is full of action, life-or-death challenges and microscopic warfare. It is a story of co-operation and ancient partnership, about events happening all over the Earth, in the hidden worlds beneath our feet. FEATURES A beautifully illustrated science-adventure story, created in collaboration with scientists Engages children in the invisible world of microbes 'The Science Behind the Story' section allows for deeper exploration of scientific concepts underpinning story Teacher Notes available to support the use of this book in the classroom The Small Friends Books series combines cutting-edge scientific research, rich narrative and beautiful illustrations to tell stories that describe symbiotic partnerships between microbes and larger life forms