Tania Unsworth

Gil bolts for freedom on his way to another foster-placement. When his backpack is stolen, with his treasured photograph and his hag-stone, his pursuit of the thief brings him to an island dividing the motorway, and to the ramshackle home of three other runaways. Riley and Grayson escaped an abusive parent, and with Junk, the dog, steal supplies. They tell Gil about another inhabitant, already established. Pez ran away from a cult, bringing with her stolen seeds, experience of self-sufficiency, and a conviction that isolation and silence are safer than human company.

The title of this novel is fairly self-explanatory: the protagonist, Stella, follows a series of clues that seem to suggest that her recently deceased mother was in fact a mermaid. She runs away from home intent on finding answers on a nearby island, where she gets into a pickle with her mother’s former associates.