The Stolen Lake
Joan Aiken
 After her adventures in Nightbirds On Nantucket, Dido Twite is travelling back to England on the HMS Thrush. En route, she befriends the ship's open-minded steward, Holystone. The ship changes course, landing on the coast of New Cumbria. Bound by ancient treaties between Britain and New Cumbria, they are given orders to assist Ginevra, the Queen. Travelling to Bath, the capital city, the crew learn that Ginevra wants them to help her recover a lake, which she claims has been stolen by New Cumbria's neighbour, Lyonesse. It seems that she is the same immortal Ginevra, or Guinevere, of myth and has waited centuries for the return of her king, Arthur. Unfortunately, she has attained immortality by cannibalistic vampirism, murdering and consuming local maidens. It then transpires that Holystone is an incarnation of Arthur, who for a thousand years had lain in suspended animation on an island in the missing lake. But this Arthur is not at all pleased at the monstrosity his ancient spouse has become.