Miss Marple and Mr. Stringer are witnesses to the death by heart attack of elderly, rich Mr. Enderby. Yet they have their doubts about what happened. The police don't believe them, thus leading Miss Marple to yet again investigate by herself.
During the French Revolution, a mysterious English nobleman known only as The Scarlet Pimpernel (a humble wayside flower), snatches French aristos from the jaws of the guillotine, while posing as the foppish Sir Percy Blakeney in society. Percy falls for and marries the beautiful actress Marguerite St. Just, but she is involved with Chauvelin and Robespierre, and Percy's marriage to her may endanger the Pimpernel's plans to save the little Dauphin
The Mazarin Stone, a famous jewel, acts as a magnet for crime. Holmes investigates the latest and perhaps most curious episode in its adventures.