The Final Reckoning：Book Three of The Deptford Mice

As London shivers in the grip of an icy blizzard, the Deptford Mice huddle indoors, telling ghost stories to keep the bitter cold at bay. Little do they know that this is no ordinary winter. Their most fearsome enemy has returned from beyond the grave. He plans to use his evil sorcery to plunge the world into an eternal, freezing night, and at his command the bloodthirsty rats of the sewers are stirring once more
Alone and seemingly powerless in the face of this most terrible of foes, the mice are close to giving up hope. Can they draw on their last reserves of strength to defeat Jupiter one final time, or is it already too late?

Robin Jarvis is a British children's author who has entertained (and pleasantly terrified) generations of children with his brilliantly imagined dark fantasy stories, including the Deptford Mice and Whitby Witches series. He studied graphic design in Newcastle and then worked in television and advertising making model monsters and puppets before writing The Dark Portal, the first book on the Deptford Mice series, which was the runner up for the Smarties book prize in 1989.