The Bastard Queen — Elaine Isaak

Beloved bastard of an unloved king, Fiona will do anything to please her father, even studying magic though she never shows more than a spark of talent. But the plague that grips their city sends her to work with the dying, as enmity builds between the two peoples her father has brought together. Struggling to find a cure for the plague, Fiona discovers that its emergence is no coincidence-and that her scorned suitor may be leading a conspiracy that will end in genocide. Even her father wears a false face, and every new tragedy reveals another secret set to shatter her life and her kingdom.