Yoofus Lightpaw was a kleptomaniac male water vole who was well-versed in woodland lore. He was the husband of Didjety Lightpaw, who scolded his ways, but was secretly proud of his talents. Though he was unfailingly kind, generous, and good natured, Yoofus was also prone to stealing everything and anything he could get his paws on. As a result, others treated him harshly, especially Doogy and Tam. Yoofus and Didjety owned Rockbottom as a pet.
Yoofus' first known act of thievery was stealing from the vermin camp of Gulo the Savage's horde of a hundred white vermin. He pilfered a curved sword from Captain Urfig, and also took the banner of Squirrelking Araltum and Idga Drayqueen, which the vermin had stolen earlier. He made off with these, unwittingly leaving behind a trail which resembled that of a wolverine. Gulo thought it was his brother Askor, and followed. Yoofus noticed, and began leading the vermin in circles.
He encountered Rakkety Tam MacBurl, Wild Doogy Plumm, Ferdimond de Mayne, and Tergen, who became suspicious as the banner they were searching for was in his possession. He told the squirrels that he would give them the banner, and help them rescue two kidnapped maidens, Sister Armel and Brookflow, who were in the claws of the vermin. In exchange, Rakkety Tam's claymore would go to Yoofus. Tam agreed, but didn't take the banner. He told Yoofus to go with Ferdimond and Tergen to Redwall Abbey.
Yoofus sneaked out of the Abbey with Tam's claymore and the banner of the Squirrelking, but he did not get far. Skipper spotted him and chased him into a river, dragging him back to shore by the tail. Yoofus managed to talk his way out of discipline again when he told the patrol that he had spied on Gulo, and that Gulo's plan was to attack the Abbey.
Tam's patrol had a skirmish with Gulo's horde, after which Doogy, Ferdimond, and Yoofus went off to the north. Gulo sent Dirig, the only ermine Captain in the horde, after them. Yoofus cleverly led them into a clearing which was actually a swamp. Then the trio met up with Tam and Log-a-Log Togey of the Guosim.
Tam formed a plan which involved leading Gulo and his vermin into a grove of pine trees where a bunch of crows roosted. Doogy and Yoofus did not take part in this plan, for they tripped and fell before entering the grove and were left behind. Yoofus decided to go back and plunder the vermin camp while Gulo was gone, and for once Doogy agreed. Yoofus stole the drum that Lady Melesme of Salamandastron intended to send to Redwall, but Doogy disapproved.
The two got into a fight, and were ambushed and taken captive by a small gang of vermin led by a weasel, who had enslaved the dormouse family of Muskar Muskar and Lupinia Muskar. The dormice knew Yoofus but had not yet learned he was a thief. Doogy and Yoofus sent the dormice outside, then proceeded to slay the vermin and free the captives.
Doogy and Yoofus stayed overnight at the Muskar home, but in the morning Doogy discovered that Yoofus had bolted, taking Melesme's drum and his own dirk, in addition to the vermin gang's raft. Doogy and Muskar Muskar followed Yoofus back to his own home, where they met Yoofus' wife Didjety. Yoofus made the age-old thief's excuse, "I was taking care of them for you", and Doogy took his dirk and the drum back. Doogy spied Rockbottom, and recognized him as the Walking Stone that Gulo was looking for. Doogy insisted the tortoise be brought to Redwall, so Yoofus and Didjety accompanied him.
Yoofus tried to lead them to Redwall by waterways and side streams, but got them hopelessly lost. He was temporarily banished from the party, but eventually allowed to rejoin. Doogy noticed that Yoofus was eying the drum, and made sure to keep it safe from him for the rest of the journey. When they finally arrived at the Abbey, Doogy and the drum were captured by Gulo and his horde. Yoofus, Didjety, and Rockbottom escaped into the Abbey, and safely watched while Tam battled Gulo.
After the vermin from the Land of Ice and Snow were vanquished, Skipper discovered Tam's claymore and the banner of Araltum, hidden in a riverside cave. Yoofus and Didjety returned to their home safely, taking with them the tortoise. Melanda MacBurl and her parents later visited them at their home. Yoofus again tried to take Tam's claymore, but returned it after Didjety and Armel scolded him for it.