The Return of the Scarlet Pimpernel

The Scarlet Pimpernel is the original hero with a secret identity, I guess. He is a seemingly foppish English aristocrat who dons disguises and leaves taunting poems as the Scarlet Pimpernel, rescuing Frenchmen who are headed toward beheading during Robespierre's Reign of Terror. This movie is "the return" because there had previously been another successful Pimpernel movie starring Leslie Howard and Merle Oberon. James Mason plays a secondary character.