American Kelsie McBlair falls through a gate in an ancient stone ring in the Scottish Highlands while rescuing a wounded wild cat. She and the cat and newborn kittens are besieged on the other side of the Gate by a Dark Rider and a pack of skeletal hounds. When a dying Witch bequeaths her true name and her jewel of power, Kelsie finds herself compelled to take up her sorcerous mission into the heart of Escore, the Green Valley, where magic lies in "trembling balance between the forces of Light and those of the Dark."
Andre Alice Norton (1912-2005) was an American science fiction and fantasy author (with some works of historical fiction and contemporary fiction) under the noms de plume Andre Norton, Andrew North and Allen Weston. Norton published her first novel in 1934, and was the first woman to receive the Gandalf Grand Master Award from the World Science Fiction Society in 1977, and won the Damon Knight Memorial Grand Master Award from the Science Fiction and Fantasy Writers of America (SFWA) association in 1983.
Andre Norton. Wikipedia.