Stormswept (Ingo #5)

Morveren lives with her parents and twin sister Jenna on an island off the coast of Cornwall - an island that in the long distant past was devastated by a tidal wave, its halls and people lost. Only some of those taken by the sea may not have been lost at all! Now, as Morveren and Jenna's relationship shifts and changes, like driftwood on the tide, Morveren finds a beautiful teenage boy in a rock pool after a storm. Going to his rescue, she is shocked to see that he is not human but a Mer boy. With Jenna refusing to face the truth, Morveren finds herself alone at the worst possible time. Because when the worlds of Air and Mer meet, the consequences can be terrible!