From the back cover:
After a successful plunder of the Urchinn Isles, a well deserved night of drinking is in order, during such you trade stories with a local "antique dealer" who tells of a well-financed acquaintance who is organizing an archeological dig. The "antique dealer" goes on to explain that his friend has unearthed a forgotten portal which accesses the island tomb of the ancient Sea Kings (guarded by legendary beasts, of course). The treasures are said to be plentiful and there is rumor that a peculiar magic sword was swept up from the depths to find its resting place in the halls of Blackstone Island.
From the front cover:
This module was designed for use with PLANET ERIS: Booklet 1 House Rules, and is compatible with all Classic, 0e, 1e, Original, Basic/Expert, & Advanced fantasy wargame systems, including the corresponding modern facsimiles and retroclones.
Within are detailed maps of 2 complete dungeon levels, monster matrices, and numbered encounter keys with fully detailed room descriptions. This module is suitable for use as a stand-alone adventure, or as an insert into a larger fantasy wargame campaign.