Book II, Chapter 24 of A Tale of Two Cities opens in August 1792, three years into the French Revolution. The monarchy has been suspended, the aristocracy has scattered, and French emigrant nobles now cluster around Tellson's Bank in London, their former wealth reduced to gossip and grand threats of revenge against the revolutionaries.
At Tellson's, Charles Darnay tries to dissuade the elderly Mr. Lorry from traveling to the bank's Paris branch to safeguard critical documents. Mr. Lorry insists he is the only person with the knowledge and authority to sort and protect the papers, and announces he will depart that very night with Jerry Cruncher as his bodyguard. Darnay privately admits he wishes he could go to France himself, feeling that as a Frenchman who sympathized with the people and renounced his aristocratic privileges, he might be able to counsel restraint.
Meanwhile, the blustering lawyer Stryver holds court among the emigrant nobles, loudly condemning the unknown Marquis St. Evremonde as a traitor to his class for abandoning his estates to the revolutionaries. Darnay, whose secret birth name is Evremonde, is stung by the insults but cannot reveal his identity. When a letter addressed to "Monsieur heretofore the Marquis St. Evremonde" arrives at the bank and no one can identify its recipient, Darnay quietly claims it.
The letter is from Gabelle, the caretaker of the Evremonde estate, now imprisoned in the Abbaye and facing execution for the "crime" of serving an emigrant. Gabelle pleads desperately for Darnay to return and testify on his behalf. The letter acts as the final pull of the "Loadstone Rock"—a magnetic force Dickens uses as a metaphor for the irresistible compulsion drawing Darnay back to France.
Convinced he can save Gabelle and perhaps even moderate the Revolution's violence, Darnay resolves to go to Paris in secret. He writes farewell letters to Lucie and Dr. Manette, tells neither of them his plan, and departs on the night of August 14, 1792, strengthened only by Gabelle's desperate cry echoing in his mind. The chapter marks the pivotal turning point that propels the novel into its third book and Darnay into mortal danger.