Sarah meets with her mother, Ada, over shopping and a meal at a café. Ada gradually gets Sarah to tell her the whole story about her relationship with Billy Prior. Ada scolds her daughter for having sex so soon. She warns her that condoms are not reliable and that if she gets pregnant, she is in big trouble. Ada does not believe in love between a man and a woman; she raised her two daughters by herself. But she considers marriage "the sole end of female existence" and she would like nothing more than to see her daughter walk down the aisle with a man of dependable income.
Sassoon meets with Graves in a bar for some lunch. He tells Graves that he has agreed to go back to active service if they promise to send him to France. Sassoon implies that Graves has no real courage, as he simply goes along with whatever the army tells him to do despite the fact that he claims to feel that the war is wrong. Graves lectures Sassoon on the importance of behaving in a gentlemanly way and keeping one's word, no matter how one's ideas may have changed. Graves changes the tone of conversation and tells Sassoon about an old friend named Peter, who was caught soliciting himself outside barracks. Peter will be sent to Rivers to be cured, and Sassoon is slightly taken aback. Graves says that since he heard about what happened to Peter, he decided to write to a girl named Nancy. Graves wants to make it clear to Sassoon that he is not (or no longer is) a homosexual.
Sarah and her friends go back to the munitions factory for a night shift. They talk about how many men in the army are homosexual, and joke that some of them have never been around women in their lives. As they are working, Sarah notices that Betty is not around. Lizzie says that Betty, realizing that she was pregnant, used a coat hanger at home to try to abort the baby. Instead, she punctured her bladder and was taken to the hospital, where the doctor strongly reprimanded her for what she had done. The girls go back to work.
Rivers finishes his nightly rounds and goes in to visit his last patient, Sassoon. Sassoon tells him the news about Peter, Graves's friend. Sassoon was hurt that Graves should make it so clear that he finds homosexuality disgusting. Sassoon is also upset that they are sending Peter to a psychiatrist to be "cured"; he thought that people had been growing more tolerant. Rivers explains to him that in wartime the powers that be want to make it very clear that there is a right kind and a wrong kind of love between men. They do this by punishing what is deemed the wrong kind. Rivers advises Sassoon to keep his private life private, or else he may find himself to be considered an enemy of his own country.
Prior stands in front of the Board who decides whether or not he is fit for duty. He is conflicted between wanting to go and prove himself a man and wanting to save his own life. When the Board asks him whether he feels he is physically fit for service, he does not respond; he has no idea what to say. Outside the room, several patients, including Sassoon, are waiting to go before the Board. Sassoon gets tired of waiting, so he leaves.
After the Board session, Rivers finds Prior crying. He has been granted permanent home service. Prior is ashamed and upset that he will never know what kind of officer he could have been. Rivers tries to assure Prior that there is nothing at all to be ashamed about; he has been through hell, and it is understandable that he should suffer "nerves" because of it. After all, it is Prior's asthma, not his psychological state, that got him permanent home service. Prior admits that Rivers reminds him of his mother. The two men part on good terms.
Late that night, Sassoon returns to the hospital and is sent up to talk with Rivers. Rivers is angered that Sassoon was so disrespectful to the Board; he demands a reason why he walked out. Sassoon apologizes and admits that he was afraid. He had no idea where he was going or how he would get there when the Board's decision had been made. Sassoon told Rivers that he considered going down to London to see Dr. Mercier, another prominent psychiatrist, to get a second opinion. In case Sassoon went back to France and continued his protest, he figured that the government would try to make the excuse that he had a relapse of mental problems. With opinions from two prominent psychiatrists that he is sane, Sassoon thought he would be better protected. Nevertheless, Sassoon assures Rivers that he does want to go back to France. Rivers promises to do what he can to make that possible.
Within Regeneration there are many plot lines going on at once, some of which intersect in important places and some of which they do not intersect at all. Structurally, the novel is separated into four main parts, each containing several chapters. Within those chapters, the story is further broken down, switching from scene to scene in order to keep up on all the plot lines. For example, in Chapter 17, the scenes change four times: Sarah and her mother, Sassoon and Graves, Sarah and her female friends, and finally Sassoon and Rivers each consecutively take the spotlight. Barker uses this technique to allow themes to carry across plot lines and characters. In Chapter 17, Sarah is upset when she hears about Betty's botched abortion, fearing that she herself might end up in the same situation. Similarly, after hearing about Peter, Sassoon is worried that he too might be sent for punishment for his homosexuality. By having unprotected or illicit sex, respectively, both Sarah and Sassoon endanger themselves. Together, they face a similar fear of societal condemnation. The narrative design of the chapter allows Barker to present these problems as situations for comparison, subtly allowing us to draw our own conclusions.