Under Illefarn (Advanced Dungeons and Dragons/Forgotten Realms Module N5)

There's nothing going on that a member of the renowned Daggerford militia can't handle. Except that the Shining River has turned green, the cattle are dying. Except that the Elf King of Laughing Hollow, a place where no human dares to go without fearing for his life, is asking the militia for help. Except that strange substances are oozing from the fissures caused by a recent earthquake. Except that the earthquake also has opened an entrance in the cliffs around Laughing Hollow that might lead to the fabled dwarf mines of Illefarn.