Ailsa's mum is ill, not the first time, so they spend the summer with her aunt and uncle. Aunt Bertha, Uncle Nod and their dog Moxie live on an island off the coast, by a beautiful fishing village surrounded by beaches and clifftops. Ailsa and Moxie spend their whole time there exploring these beaches and cliffs, until one day they find a hidden cave. Inside the cave, they find Hefring, a strange woman not keen on strangers. Ailsa slowly gets to know who Hefring is. She is a selkie, a mermaid, a billow maiden from ancient myth. However, she is stuck on land and slowly dying. It is up to Ailsa and her new friend Camilla to save her, but there are plenty of obstacles in the way - not least Ailsa's own fears and her mum's illness. The Billow Maiden is a beautifully told tale of friendship, family, healing and transformation from a stunning new writer for children.