When miners in Termalaine, one of the towns of Ten-Towns, unknowingly discover a new source of the mysterious and powerful chardalyn, powerful foes from the Underdark take note and begin their own investigation. Strange things begin to happen around Termalaine, and heroes find themselves drawn into a mystery with few obvious answers. Can they discover the truth of the sinister mechanisms at play before Ten-Towns is destroyed--or worse, before the mind flayers learn everything they're after?
This adventure is a one-shot horror-mystery designed to scale level levels 10 to 20, optimized for level 15. In it, heroes must solve a unique mystery and battle deadly mind flayers in a fight for the future of Termalaine. As an unofficial prequel to Rime of the Frostmaiden, this book easily stands alone but is also designed to provide further hooks into the ongoing story of Icewind Dale and Rime.
- from the publisher's blurb