Agatha Christies Seven Dials Mystery (2004)

When two mysterious deaths mar an otherwise pleasant weekend in the English countryside unflappable flapper Lady Eileen Brent teams up with the dashing Jimmy Thesinger to solve the dastardly deeds Their sleuthing leads them into a world of espionage and international intrigue as they discover a secret society known as The Seven Dials and the attempted theft of topsecret government documents