What is the conversation among Sydney Carton, Jerry Cruncher, and John Barsad (the spy)?

In Book III, Chapter VIII, Miss Pross and Jerry Cruncher are shopping, unaware that Darnay has been arrested again. They coincidentally enter the Defarges' shop looking to purchase wine. Miss Pross sees a man in the shop and screams, because she recognizes him as her brother, Solomon Pross, who is now an officer of the French Republic. Jerry Cruncher is equally shocked because he recognizes the man as John Barsad, the English spy. He is trying to think of this name aloud, when Sydney Carton passes by and supplies the name for him.

Carton asks to speak to Barsad alone and reveals that he is a turnkey in the Conciergerie. This is where Carton recognized his face. He followed him back to the wine-shop and now asks him to accompany him to Tellson's Bank for a talk. There he meets Mr. Lorry, who also recognizes him as having been a witness at Darnay's trial. Carton tries to use what he knows about Barsad (the fact that he is currently employed by the Republican government under a false name but was formerly employed by the English government-which would lead the French government to believe he is a spy) to help free Darnay. He threatens to denounce Barsad, adding that he recognizes the man with whom Barsad was talking as Roger Cly. Barsad tries to claim that Cly is dead and had a funeral back in London, but Jerry Cruncher interjects, saying that he looked in that coffin, and there was no body in it. Despite the fact that he grows defensive when asked why he knows this, Cruncher sticks by his assertion, and Barsad gives up and agrees to help Carton.