Dondal was the nephew of Chief Councilor Tu. He is described as a slim, foppish young man with dark eyes and a pleasant smile. He had a positive reputation as a man of discretion who never repeated what he heard at court, and for this reason he was admitted into places where he otherwise would not have been allowed.[1]
Dondal maintained an aristocratic lifestyle and fell heavily into debt. As a result, he sold his loyalty to Verulian interests and became a traitor to Valusia. He worked with a team of conspirators who had been clandestinely sent into Valusia by the king of Verulia (who is not named) with the purpose of capturing Kull.[1]
Dondal stole Tu's signet ring used by the Councilor to put his royal seal on important documents. Dondal used the seal to forge a letter in Tu's handwriting and had the letter delivered to Kull. It instructed the king to follow the bearer of the message to the Accursed Gardens two miles east of the city. Kull, believing the letter was written by Tu, fell for the ruse and was taken prisoner at the Gardens by the conspirators.[1]
Kull was soon set free by the noblewoman Delcartes, who had also been captured. He then engaged in battle with the Verulians and their gang of soldiers, with the help of the Farsunian adventurer Dalgar who arrived soon after and fought alongside Kull. Brule and his Pictish warriors arrived later, and Dondal was killed by Brule after a fierce exchange of swordplay. The deaths of the conspirators led to the failure of the plot.[1]
While working with the conspirators, Dondal wore a black hood to conceal his identity and insisted on being referred to as the Masked One in order to discourage his cohorts from speaking his name and revealing it to others.[1]
Even after the fact, Tu remained completely unaware of his nephew's treachery. To spare his feelings, Kull and Brule made Tu believe that Dondal died as a hero fighting for Valusia.[1]