The Edinburgh Festival brings together artists from all over the world, and Cowrie is among them, telling stories and giving readings. But even Cowrie can't anticipate the chemistry that will begin when a group of traditional storytellers sets off to the Orkney Islands with Ellen, to stay at her coastal family cottages. For Ellen turns out to be Morrigan, and Morrigan is a selkie, living in the sea and on land. As an ancient mystery unravels, Cowrie and Sasha must turn detective to discover the truth behind Morrigan and the song of the selkies.