Coastliners by Joanne Harris

Mado has been adrift for too long. After ten years in Paris, she returns to the small island of Le Devin, the home that has haunted her since she left. Le Devin is shaped somewhat like a sleeping woman. At her head is the village of Les Salants, while its more prosperous rival, La Houssiniere, lies at her feet. Yet even though you can walk from one to the other in an hour, they are worlds apart. And now Mado is back in Les Salants hoping to reconcile with her estranged father. But what she doesn't realize is that it is not only her father whose trust she must regain.