A dwarven monastery has long contained a terrible evil known as the Matron of Pestilence, imprisoning her to prevent her unholy infection from spreading across the land. Now, the monastery has fallen to the schemes of those faithful to the Matron and an insidious corruption threatens the place from within. The party must enter the infected religious sanctuary to track down the means of dispatching the Matron of Pestilence forever before they are caught in the grip of her festering hand. Puzzles, traps, and twisted forms of life stand between them and victory, and the adventurers have a hard climb ahead of them to overcome Pestilence at the Peak of Law.