A young female squirrel named Trisscar (mostly called Triss) is a slave to a royal family of white ferrets who live in a castle on an island. Along with two other slaves, Shogg (a male otter) and Welfo (a female hedgehog), Triss escapes from the island. The evil ferrets chase Triss and her friends. Triss and Shogg join forces with warriors from Redwall Abbey and the mountain Salamandastron, and together, the woodland creatures fight rats, ferrets, snakes, and more in their fight for freedom.