While they're out on their errands, Miss Pross screams when she recognizes her brother, Solomon Pross, disguised as a French republican. Solomon tells her to be quiet, or else she'll get him killed. Jerry, meanwhile, also thinks he recognizes this man, but can't quite remember his name.
As an unthinking English patriot, Miss Pross has never questioned her brother's integrity, but as this chapter will show, he's a traitorous opportunist in an ugly political world.
Sydney Carton, appearing out of nowhere, tells Jerry the name he is trying to remember: John Barsad. Having arrived in Paris a day earlier, Carton explains, Carton chanced upon and recognized Barsad from Charles Darnay's English trial. Carton also learned that Barsad was serving as a French government spy working in the prisons.
Dickens's novels are often filled with extreme coincidences, such as Carton and Barsad's sudden appearances. Though one can guess that Carton came to Paris out of concern for Lucie.
Carton and Jerry escort John Barsad to Tellson's Bank, where Mr. Lorry also recognizes him. Carton says he has a plan to help Charles. He then blackmails Barsad, threatening to reveal him as a spy of the French government and as a former English spy, both of which would enrage the revolutionaries. Carton then reveals that he has seen Barsad associating with another known English spy: Roger Cly.
Because Carton has nothing to lose, he can play the dangerous game of counter-intelligence. Carton wants to save Charles in part for Charles's sake, but to a larger extent because of his feelings for Lucie. Recall his promise to Lucie at the end of Book 2, Chapter 13.
Barsad grins: Cly is dead, he says. He then takes out a certificate of burial and says he buried Cly himself. To everyone's surprise, Jerry angrily objects that Barsad had placed "shameful impositions upon tradesmen," and then reveals that Cly's body wasn't in his coffin. Barsad realizes he's caught and agrees to help. Carton takes him into an adjoining room to talk.
Jerry's secret job as a "resurrection man" saves the day! But note that it takes being caught in a lie to get Barsad to help Charles. There is no honor among spies. And Barsad has no concept of sacrificing himself to a higher cause.