From the publisher:
It has been four seasons since Mariel, the warrior-mouse daughter of Joseph the Bellmaker, and her companion, Dandin, set off from Redwall to fight evil in Mossflower. Nothing has been heard of them since. Then one night, in a dream, the legendary Martin the Warrior comes to the Bellmaker with a mysterious message. Clearly, Mariel and Dandin are in grave danger. Joseph and four Redwallers set off at once to aid them. As they push over land and sea, they cannot know the terrible threats they face. Will the Bellmaker and his companions arrive in time to help Mariel and Dandin?
