The Taggerung Redwall, Book 14 (Unabridged)

When the outlaw clan of foxes, weasels, stoats, and other vermin led by vicious ferret Sawney Rath kidnaps an infant otter of Redwall to serve as their Taggerung - a fierce warrior who no beast can stand against in battle - they have no idea what they're getting into. Trained in all the deadly arts and able to outfight, outrun, and outthink any clanbeast, the Taggerung grows up with only one slight peculiarity: he refuses to kill! What's a vermin clan to do when its greatest warrior is too pure of heart to live among them?