Sylvan the water vole is desperate to explore the world outside his burrow and the time has finally come. His protective mother leads her children around her territory but while Sylvan is ready to dive in head first, his brother and sisters are not so sure. Despite its lush plants and cool waters the outside world is a frightening place full of predators and enemies and learning to navigate its dangers takes time and experience. But when their mother is suddenly taken by a terrifying unfamiliar beast it is up to the children must fend for themselves, and with a hunter on the loose their only hope is to leave their home behind and set out to find the mysterious ‘wetted land’. Sylvan must trust in the great river to guide his family to safety, but even the river that once offered so much security is changing and the river singers must listen to its warning.