From the back cover: "Evil Tide is the first of an adventure trilogy (continuing with Night of the Shark and concluding in Sea of Blood) that pits brave adventurers against the evil race called 'sahagin' by the air-breathing races. The sahuagin adventure trilogy can be played separately or linked together to form a seamless epic-length adventure. The sahuagin trilogy supports Sea Devils, a Monstrous Arcana sourcebook providing invaluable, fascinating, and immediately applicable supplementary information."