From the front cover:
"Concerned by stories of the resurfacing of the Isles of Woe, Warnes Starcoat is sponsoring an expedition into the Brass Hills to explore a site called the Zochal. According to the Nesser Opuscule, only surviving fragment of a greater work attributed to Tzunk, the Zochal is an echo point for the planar confluence that infuses the once lost sunken isles. What does that mean? That is exactly what the Circle of Eight wants you to find out. An adventure for characters level 3-12."