Ingo by Helen Dunmore (audio)

Sapphire lives with her brother Conor in a tiny beach cottage on the edge of the Cornish sea, their days are idyllic, swimming and playing in and around their secret cove below the house. The only shadow is their lost father and their sad mother who works all hours as a waitress to pay the bills. Then Conor begins to absent himself and Sapphire, naturally saddened and curious, follows him to the sea edge where he sees her taking with a mysterious girl. One day, in frustration, she pursues what she thinks is him but coming up close realises the boy is a stranger, and very strange at that. The boy and girl draw Conor and Sapphire into the world of Ingo where myth, family history and their own lives change shape irrepably.

Great storytelling, but a bit constrained and clearly the first of a series (a quadrology in this case), but I can't wait to read The Tide Knot.

I should mention that I've been listening to this on a Playaway audiobook, a dinky little thing that is basically a preloaded mp3, much easier than loading onto my mp3 player which is a bit archaic and doesn't necessarily get the discs in the right order...