When Ailsa’s mum becomes ill, the two of them spend the summer with her aunt and uncle on the faraway island, a beautiful fishing village surrounded by beaches and clifftops. Ailsa and Moxie the dog spend their days exploring until one day they discover a hidden cave and in it, Hefring – a strange woman not keen on strangers. Slowly Ailsa gets to know who Hefring is – a selkie, a billow maiden – and with the help of her new friend, Camilla, it falls to them to retrieve Hefring’s sea-skin. But there are obstacles ahead of them, and it is not only Hefring who is at risk but Ailsa’s mother too. A beautifully told tale of friendship, family, healing and transformation, from a stunning new writer for children.