Sorcha is the seventh child of a seventh son: but as a daughter rather than the seventh son he desired, she is neglected, having also caused the death in childbirth of her beautiful mother Niamh. Her six brothers, however (beautifully delineated characters, each of them), devote themselves to her and support her education in plant-lore, healing and natural magic.
All is fine until the sensuous but evil Oonagh seduces their father, the warlord Colum, and sets about systematically breaking apart the family. When she catches the children plotting against her, she turns the brothers into swans, and Sorcha is set an impossible task in order to free them from her wicked spell.
This is an old Celtic legend in its own right: brilliantly evoked and brought to life, amid raids by both the Britons and the Vikings. In the process of her task (which binds her to muteness until it is accomplished), Sorcha will meet and fall in love with a Briton warlord (the enemy), and against all odds their love will triumph.
Like Marion Zimmer Bradley's Mists of Avalon or Jean Auel's Clan of the Cave Bear, this is first-rate historical fantasy that can have the widest possible appeal, taking in also the readership of historical fiction writers like Mary Stewart (The Crystal Cave), Mary Renault (The Persian Boy) and Anya Seton (Avalon).