Fantasy in Four Parts - Evil

A party of adventurers have been sent on a mission to find the source of the evil which is effecting their lands. They find that long ago drow elves, along with a people from over the seas, had taken a nearby country by force. They had been defeated, but not destroyed. It is the descendants of the drow elves who are trying to open a pandora's box of elemental powers that is the source of the evil. After overcoming many challenges and problems they at last find and close the evil, only to be double crossed by an unstable cleric.