The night before Lucie Manette is to marry Charles Darnay she and her father sit under the plane tree in their yard and she reassures him that he love for Charles and all the ties that marriage will bring will not intrude upon her feelings for her father. He assures her that he knows this to be true and that her marriage will only make him happier. He speaks of the time he spent in prison, something Lucie has only heard him mention once before, and describes how he imagined what his child might be, son or daughter, and worried that they would never know him. He explains that in his furthest flights of solitary imagining he never would have believed that he could be as happy as his present life has made him. Later that night Lucie sneaks into her father's bedroom and, placing her hand on his breast, she prays that she will always be true to him.
The morning of the wedding Mr. Lorry and Miss Pross fuss over the beautiful bride while Dr. Manette and Charles Darnay confer in the adjoining room. When Mr. Lorry suggests that he should have married before he grew old, Miss Pross insists that he was born to be a bachelor. Mr. Lorry promises Lucie that he and Miss Pross will take good care of her father while she and Charles spend two weeks honeymooning in Warwickshire and will send him to Wales to join them in good health. When Darnay and the Doctor emerge from their conference Mr. Lorry notices that the Doctor is pale and seems cowed. The wedding, which is private at a small church, goes smoothly and after breakfast the newly married couple are on their way. Mr. Lorry again notices the doctor's changed demeanor and when he returns later in the evening he is alarmed to find Doctor Manette at his old occupation of making shoes. The doctor does not recognize either Mr. Lorry or Miss Pross. Mr. Lorry, for the first time in his life, takes a leave of absence from Tellson's in order to attend to his sick friend. For nine days he tries to bring the doctor to his senses by making small talk about ordinary affairs.
On the morning of the tenth day Mr. Lorry awakes in the doctor's room where he had unintentionally fallen asleep. The doctor has returned to normal but is not aware that nine days have passed since Lucie's wedding. After breakfast Mr. Lorry engages his friend in a discussion regarding a hypothetical friend who recently experienced the recurrence of an old mental debility. The doctor understands that they are in fact discussing himself but continues with the conceit. When the doctor learns that Mr. Lorry's "friend's" daughter is unaware of the relapse he is very thankful. The doctor admits that the relapse was foreseen by its subject and dreaded. The doctor expresses his belief that the relapse might not return. Mr. Lorry asks if perhaps if his friend works too hard and the doctor denies that this is the cause. Mr. Lorry then suggests that the tools that accompany the relapse (meaning the shoemaker's tools and bench) should be thrown away. The doctor argues that they were once so important to the subject's survival as to have become dear to him. He relents, however, that they should be disposed of in the subject's absence. Accordingly, as soon as the doctor has left for Wales to meet his daughter and son-in-law, Mr. Lorry with Miss Pross assisting utterly destroys the shoemaking implements.
Soon after Charles and Lucie return their first visitor is Sydney Carton. He pulls Charles aside and asks him if they could be friends so he might have the privilege of calling upon the couple informally about four times a year. Charles asserts that they have always been friends, which Carton dismisses, but readily accepts Charles' offer to call upon them whenever he feels the need. Later that night Charles makes comments about Carton being reckless and careless. Later, in private, Lucie begs him to show more leniency in his opinion of Carton and expresses her belief that he is capable of great things. Charles is touched by the reminder that while they are happy Carton is miserable. He promises to remember her advice.
Analysis of Chapters 17-20
The doctor's mental relapse following his private conversation with Charles Darnay sets the stage for a collision between the doctor's past and Charles' aristocratic family. Mr. Lorry and Miss Pross are revealed are shown to have softened in the years of they have spent with the Manette family. Their easy banter and shared joy in the union reflect a deeper emotional life than either had been comfortable expressing at the beginning of the story. As such, it is appropriate that they share in the destruction of the doctor's shoemaking tools - the most tangible sign of his former life and in their view the best service they can do for the family. Their sensitivity to the dynamics of the family, evidenced by the secrecy they maintain around the doctor's relapse, endears them to Dr. Manette when he has recovered his senses. This desire to protect his daughter from his relapses coupled with his tacit permission to destroy the shoemaking implements indicates that Doctor Manette is hopeful of overcoming his past and its associations with Darnay's ancestry. Sydney Carton's somewhat awkward request to be permitted to visit the family demonstrates the degree to which their happiness has become necessary for his survival. That Lucie's sympathy for him is genuine is evidenced by her defense of his character to her husband.