The Caverns of Kalte (Lone Wolf, Book 3)

After defeating Darklord Zagarnas invasion, Sommerlund has begun rebuilding and little scars of war remain after one year. Work on rebuilding the Kai Monastery was about to commence when disturbing news from the north came. The merchants returning from summer trading to Kalte told of Brumalmarc, leader of the Ice Barbarian, has fallen to a hunch-backed magician. The description fit non-other than Vonotar, the former wizard from the Brotherhood of the Crystal Star, who betrayed Sommerlund and helped the Darklord Zagarna in the invasion and massacre of the Kai Order.