Brother and sister, Judith and Peregrine, find themselves wards of the fashionable and autocratic Earl of Worth. His behaviour infuriates the lively Judith, but she also sometimes suspects him of having warmer feelings towards herself. Her brother becomes engaged to be married and almost immediately suffers from unexplained illness, an attack by highwaymen, and is forced into a duel, which is fortunately stopped in time. Judith doesn't know who to trust, but her cousin, a suitor for her hand, tries to convince her to suspect the Earl. This story combines Georgette Heyer's skill in portraying the Regency period, and her skill in writing a mystery. Another of my favourite Heyers.
