How is Mr. Lorry going to save Lucie, Little Lucie and Dr. Manette? On what is Mr. Lorry to dwell when he explains the danger to Lucie? Why will this help him save them (From Book 3 Chapters 11-15)

Carton explains to Mr. Lorry about Madame Defarge's intention to denounce the whole family using the testimony of the wood-sawyer, who will swear they were signaling to the prisoners. He urges Mr. Lorry to ready Lucie and her daughter to leave the city the next day at two p.m. and to leave as soon as Carton appears to get in the carriage. Carton leaves but lingers in the courtyard, saying a goodbye to Lucie's window.