The Dark Ground by Gillian Cross
Robert is alone, in a strange jungle. He has no food, no shelter, no warmth. Unfamiliar creatures are roaming about - and he's not even sure how he got there...Following the story of Robert's struggle for survival, through to his extraordinary realization of where he is and what has happened to him, and then to his perilous journey to find his way home, this is an incredible adventure story full of suspense and surprises. This builds on the great success achieved by Gillian Cross's previous novel "Calling a Dead Man". Gillian Cross is one of the UK's top children's authors, and has won every major children's book prize. She is highly acclaimed internationally.