Nerilka's Story by Anne McCaffrey

The latest of McCaffrey's romantic Pern novels expands on the tale of a minor character in Moreta: Dragonlady of Pern. Young Nerilka is considered unattractive and overly serious in her own hold, where her peremptory father installs his mistress immediately after his wife's death. Angry and frustrated, Nerilka uses her medical training and her access to the supplies her father is hoarding to help combat the plague sweeping Pern, which has already claimed her mother and sisters.