Gaudy Night by Michael Bakewell

A celebrated mystery writer and former defendant returns to the Oxford women’s college where she was once a student to work among scholars and is drawn into a tense campaign of anonymous letters, vandalism and intimidation that threatens the intellectual life of the college; as she helps uncover motives and identity, she confronts questions about conscience, the responsibilities of scholars, and her own feelings about independence and a complicated romantic relationship with an aristocratic investigator who pursues her.