The city of Port Regan maintains a lighthouse on a small island in the Picaroon Sea, approximately twelve miles south of Port Regan. The lighthouse is essential to preventing trading ships from running aground on treacherous shoals in the bay, but two nights ago, the lighthouse’s light went unexpectly dark. In two weeks, the prominent merchant Yvonne Voclain will be coming into port with her fleet and the council needs to be sure that her ships will be safe in arriving on the docks. To expedite matters, Captain Joan Davies, head of the city watch, asks the party whether they are willing to investigate.
Unbeknowst to the town guard, the lighthouse has been attacked by a pair of sahuagin priestesses, Hexanqi and Heptranqi, and their sahuagin followers. They have recently arrived in the region and they have killed the lighthouse keepers and are currently working to destroy the lighthouse beyond repair so that they can then prey on shipping that runs afoul of the shoals. Hexanqi is also looking for secrets from a lost triton civilization, which she hopes to plunder for her foul purposes.