Wengle Brookrudder was a young male otter that came over the eastern sea with his mother and some other creatures from the lands beyond for the warmer climate. His best friend was a young shrew named Riddy. The ship that he was on, The Rosalie, was attacked by Rackorg Vinn and his corsairs. When Wengle saw the weasel captain standing over his mother's body, he attacked him. However, Wengle was knocked unconscious by the searat Scumtail, and was thrown overboard. He washed up on the Mossflower shore where he was found by Corkly G. Battlescut.
The hare gave him food and shelter and Wengle told him of a message which an old squirrel on the Rosalie named Hampa Swiftbow had told him just before he died. "Go to the Longbrush Glen." Corkly knew the place and they sent off the next morning. On the way, they were attacked by a group of vicious Swamp Lizards. The pair fought their way out but were later that night they were captured by the lizards and were almost killed, when the sparrowhawk Keekag came to their rescue. She showed them the way to the Longbrush Glen, where they met Spruce Longbrush, the squirrel leader. Soon after, they were attacked by the Pineshadows, and as Spruce, Corkly, and the rest of the squirrels fought off the pine martens, Wengle escaped with Spruce's two children, Garrow and Oakflower. After the battle, Oakflower was captured by the searat Gorv and his fellow vermin that had deserted Rackorg Vinn. She was rescued by the Longbrush squirrels and later in Spruce's tree-house, the otter told him about a dream that he had the night before the corsairs had attacked his ship. Spruce knew that Martin the Warrior had given him the dream and the group went to Redwall Abbey to see if Wengle was the next Redwall champion.
Meanwhile, Rackorg Vinn had come to land and had joined forces with the Pineshadows to attack and take over the Abbey. Wengle, Corkly, and the Longbrush squirrels helped to defend Redwall and since Wengle did not know much about fighting with a sword, Spruce and Corkly taught him how. That night, the vermin attacked Redwall Abbey and Wengle fought alongside Corkly in the battle. The small defending force would have been crushed had it not been for Riddy, who had been captured by the sea-vermin as a galley slave and had escaped and come with an army of slaves. Rackorg Vinn then wounded the shrew and Wengle attacked the weasel, shattering his scimitar blade. He then chased the corsair out of the Abbey and onto the beach where the otter slew him by throwing the sword at Vinn while the weasel was climbing back onto his ship.
When Wengle got back to Redwall, he was greeted by both joy and tragedy. He found that his mother had not been slain, and was now here at Redwall. He also discovered much to his sorrow, that the young squirrel Garrow, who had become his good friend, had been killed when he fell off the Abbey wall with Valkarano, the Lord of the Pineshadows. In the next few days, the Redwallers had a feast and Wengle became the Redwall champion.