From the campaign:
There once was a monastery perched high on a slope of the mountain called Hvitr’s Horn. The warrior-monks who dwelt within were dedicated to the god Hvitr—lawful god of storms and justice—and entrusted with the stewardship of holy artifacts and texts. But above all else they were gatekeepers; for Hvitr’s Horn was an active volcano, and thus (like all active volcanoes) a gateway to Ellorash, an elemental plane of fire. The end of this brotherhood came with an eruption that spewed forth the Flaming Host of Ellorash, an otherworldly legion led by the demi-goddess Gildarthe. Legend holds that Hvitr himself descended from the heavens to beat back Gildarthe and seal the planar gateway, but not before the monastery and all within were drowned in a flood of lava.
Now, 300 years later, the steading of Meervold, at the foot of Hvitr's Horn, has entered a dark time. Villagers are disappearing. Strange lights are seen on the cold slopes. Distant screams echo through the night. The Council of Elders is broken and powerless, and those who have not fled Meervold remain only because they are paralyzed with fear.