The theme of duplicity runs throughout "A Tale of Two Cities." The encounter of Sydney Carton with the brother of Miss Pross, Solomon Pross/aka Barsad is a minor example of this duplicity. Carton recognizes Barsad at the prison where Charles Darnay/Charles Evremonde is being held as the witness from the treason case against Darnay in England. (This coincidence is Charles Dicken's way of showing the workings of Providence.) Taking advantage of this knowledge, Carton tells Barsad that he will not identify him to the Red Culottes (the revolutionaries) as the double spy that he is if Barsad will provide him with access into the prison. When Sydney Carton obtains this access, he drugs Darnay and switches places with his double so that Darnay can escape Paris with his family.