Nerilka's Story & The Coelura, Paperback/Anne McCaffrey

It was in Moreta's time - a time of legend, of heroic valor, of terrible Threadfall and the Great Plague that devastated both Holders and Dragonfolk. For Lady Nerilka of Fort Hold, the tragedy was twofold, for with the death of her mother and her sister, her father's mistress took possession of the Hold.