City of Sorcery

Haunted by mysterious images of hooded figures, Magdalen Lorne, chief Terran operative on Darkover, pursues a quest not only to the frozen ends of the physical world but also to the perilous limits of the spiritual world. And there she is tested by the evil sorcery of the Dark Sisterhood.

City of Sorcery is in the Darkover series and is a sequel to Thendara House.