A young girl disappears, presumed drowned on the Cornish coast while on holiday. Meanwhile, the British Minister for Defence is coming to the same area to stay. His children, the 3 Js, make some startling discoveries while birds are behaving in a sinister way. The nation's security lies on a knife-edge: a comet is on course to collide with Earth, and there are anonymous threats of terrorism. The minister and his wife return to London, while James, Jo, and Jake ride to Lyonesse, where they meet knights of the legendary Round Table. Their perilous mission takes them to the Lady of the Lake, and...