An elderly family friend commissions Frances to find Helen, a stunningly beautiful actress who vanished 30 years ago. Taking on the role of the Lady Sherlock, with her loyal maid Mallow drafted as her Watson, Frances immerses herself in the glamorous world of Edwardian theater and London's latest craze—motion pictures. Frances' first stop is the venerable Emerald Theatre, where aging actors are still in love with the memory of the beguiling Helen. It seems like a dead end—but one of Helen's old suitors is suddenly murdered. Frances and Mallow beat both the police and killer to a box of subtle clues. However, a stalker, another old suitor of Helen's long presumed dead, threatens them. Will Frances' latest hobby, a study of Japanese martial arts, be enough to save them? Undaunted, Frances and Mallow follow their leads, and along the way get some advice from George Bernard Shaw, star in a motion picture, and joke with King Edward VII. Clues eventually lead them to a forgotten grave outside of London, which contains a mysterious biblical inscription—and a shocking secret. Frances finally assembles the pieces, and with Mallow as stage manager, produces her own play to uncover a decades-old conspiracy, reveal a killer—and find the remarkable Helen.