Yoofus Lightpaw was a kleptomaniac water vole, who was well-versed in woodland lore. Though he was unfailingly kind, generous, and good natured, he was also prone to stealing everything and anything he could get his paws on. As a result, other goodbeasts treated him harshly, especially Doogy and Tam. He was the husband of Didjety Lightpaw, who scolded his ways, but was secretly proud of her husband's talents. Yoofus and Didjety owned Rockbottom as a pet.
Yoofus' first known act of thievery in Rakkety Tam 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 ran into Rakkety Tam MacBurl, Wild Doogy Plumm, Ferdimond de Mayne and Tergen the Goshawk, who were immediately suspicious because he had the banner which they were searching for. 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, into the bargain. The price for this deal was Rakkety Tam's claymore. Tam agreed, but didn't take the flag yet. He told Yoofus to go with Ferdimond and Tergen to Redwall Abbey.
Yoofus sneaked out of the Abbey with Tam's claymore and the flag 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 three met up with Tam, and with 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 which Lady Melesme of Salamandastron meant 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 family's 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 recognised him as the Walking Stone which 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 sidestreams, 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 did get to the Abbey, Doogy and the drum were taken captive by Gulo and his horde. Yoofus, Didjety and Rockbottom just managed to escape and get into the Abbey, and were watching safely while Tam had his famous single combat with 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.