This adventure finds the PCs entering an ancient dwarven mine system that was converted into a prison for all things foul and dark. The mine, which previously yielded the highest quality silver, was the ideal location to imprison demons and devils because the unique nature of the silver does not allow them to teleport or plane shift. The demons cannot leave their individual prison areas. However, non-demons/devils can enter freely. Worse, the magical wards are deteriorating and the demons are on the verge of escape. Seven demon types are presented; each in a challenging scenario.