Lucy, shipwrecked on an island at 8, is forbidden to sing by guardian Norrie. On All Hallows Eve 1667, at 15, she sings, and is swept into darkness. She wakes to hear powerful men hunt Chantresses who sing magic into the world. At the Invisible College she finds sanctuary, plots to overthrow the evil Lord Protector, and distrustful scientist-apprentice Nat. Only a Chantress can overcome the Protector, and Lucy is the last in England.