The rustic folk of Blackbeach have kept their cursed heritage secret for thousands of years - they are pureblooded scions of Lost Azlant, the sunken continent across the western sea, whose bloodline eventually causes them to transform into sea-folk and obey a strange underwater entity. A local sorcerer trying to cure his people has awakened a terrible evil, locked away in a nearby Azlanti ruin for thousands of years. Now the villagers are rapidly devolving into fishlike monsters and hearing a telepathic call they cannot refuse. Can the heroes save the villagers and stop the ancient abomination before it escapes to avenge itself? An aquatic dungeon adventure for 6th-level Pathfinder Roleplaying Game characters.