The Reluctant Widow by Georgette Heyer

In this Regency-era novel, a young woman finds herself unexpectedly thrust into a world of intrigue and danger when she agrees to a marriage of convenience with a dying man to save her own financial future. However, her plans are quickly complicated by the deceased's family, a missing will, and a mysterious French spy. As she navigates her new role as a widow and property owner, she becomes entangled with the late husband's dashing and determined brother, who draws her into a risky plot to uncover espionage against England. Amidst the backdrop of high society and the threat of Napoleon, romance and adventure ensue, challenging the heroine's resolve and her heart. The 8317th greatest book of all time