Merlin's Harp - Anne Elliot Crompton

Among the towering trees of magical Avalon, where humans dare not tread, lives Niviene, daughter of the Lady of the Lake, Her people, the Fey, are folk of the wood and avoid the violence and greed of man. But the strife of King Arthur's realm threatens even the peace of Avalon. And while Merlin the mage has been  training Niviene as his apprentice, he now needs her help to thwart the chaos devouring Camelot. Nivien's special talents must help save a kingdom and discover the treachery of men and the beauty of love...