Using the light of the Mer-Moon, Cap'n Turbot sails Ryder and the pups on the Flounder to Puplantis for a Mer-Pup Mer-Moon celebration. Skye sings a lullaby she heard as a baby pup, prompting Cap'n Turbot to tell the pups the legend of a "land-lubbering" pup who was lured out to sea by the singing of the Mer-Pups and had so much fun with them that she stayed in their underwater world, which Skye had also heard of.