The hideous spirit of Jupiter, the evil cat who was once lord of the sewer rats, has returned, more terrifying than ever. Bent on revenge for his death, he is determined to turn the world into an eternal winter of hatred. The Deptford Mice feel his chilling grasp everywhere they turn. Their allies are murdered, and the prophetic bats flee, sensing impending doom. A rat army thirsty for mouse blood is building underground. And most frightening of all is that the Starglass, their magical source of knowledge and power, has been stolen by a cruel and violent hand. The mice know they face the most desperate struggle of their lives. Will anyone survive?