Merfolk and the stories about them pervade Cornwall, the seaside community where Sapphire and her older brother, Conor, live. One of the most memorable moments, in fact, between Sapphire and her father, happens when he tells her the story about Mathew Trewhella, who left his human girlfriend for the Mermaid of Zennor. So, it’s not really a surprise that Sapphire’s dad, also named Mathew Trewhella, disappears after going out on his boat late one evening. The kids believe that their dad isn’t dead, but lives now with the Merfolk, and they want to prove it. Coincidentally, they begin to be called by the sea and start swimming with the Mer. The two experience a double life as “Air” people and partly transformed “Mer” creatures. This confuses them and they begin to question who they are and what their true ancestry is—and of course they want to find their dad. When their mother gets a diver boyfriend, Roger, the kids have to decide whether or not they want to save him from certain death, or to let him follow his human fate. What’s fresh about this mermaid story is that it doesn’t try to be what it’s not; so many of the elements will be familiar to young readers, but they will get to examine Mer life from their own perspective. A gentle, pleasurable read. (Fiction. 10-14)