The preparations for Jeremiah and Ma'Shingayi's wedding begin, and Tambu becomes extremely anxious. She grows resentful of Babamukuru for "having devised this plot which made such a joke of my parents, my home and myself." She can feel her anger against Babamukuru rising up inside herself and yet, squashes it back down because she considers him to be Godlike and therefore, infallible. She amuses herself by making clay pots for fun with Nyasha. When Babamukuru goes back to the mission with Maiguru and Nyasha, he leaves Tambu at the homestead to help with the wedding preparations. Lucia continues trying to convince Ma'Shingayi to leave the homestead with her, but Ma'Shingayi has reservations. She says, "What I have endured for nineteen years I can endure for another nineteen, and nineteen more if need be." Meanwhile, Tambu and Lucia fix the damaged roof but when Babamukuru comes to collect Tambu and take her back to the mission, Jeremiah takes credit for it.
Back at the mission, Tambu continues to be an "exemplary young lady" while Nyasha keeps disappointing her father. Ma'Shingayi comes to the mission hospital to give birth, accompanied by Lucia. Lucia takes the opportunity to pester Babamukuru about Takesure and it becomes clear that she hopes to stay at the mission and get a job there. Much to everyone's surprise, Babamukuru does find Lucia a job cooking food at the girls' hostel. She also begins to go to Grade One classes in the evening. This once again changes the way Tambu views her uncle, once again.
Meanwhile, Nyasha, Maiguru, and Tambu help Ma'Shingayi plan the wedding. Nyasha takes on the task of organizing almost everything, including shopping for material to make a dress. Tambu is offended by the frenzy, feeling that it reduces her parents "to the level of the stars of a comic show, the entertainers." On the night that Tambu is supposed to return home to help start wedding preparations, she hides in the girls' hostel. The next morning, Tambu is depressed, unable to get out of bed, and apologizes to her uncle, refusing to go to the wedding. Babamukuru is furious, of course, but eventually the rest of the family goes to the homestead and Tambu is allowed to stay at the mission. After the family returns, Babamukuru punishes Tambu with fifteen lashes and two weeks of maid's work. Tambu finds a certain measure of satisfaction in her punishment, because it is the result of having stood up for herself.
Lucia visits with her new baby, Farai, and stands up to Babamukuru, insisting that he should not be punishing Tambu so severely, and Maiguru agrees with her. After Lucia leaves, Maiguru continues to argue with her husband, finally saying what has been on her mind for some time: "When I keep quiet you think I am enjoying it. So today I am telling you I am not happy. I am not happy any more in this house." Babamukuru reacts by telling her to go wherever she wants. Nyasha predicts that her mother won't leave, but she is wrong. Maiguru departs by bus the next morning. Tambu is surprised by how much this pleases Nyasha, since her cousin points out, "there was a difference between people deserting their daughters and people saving themselves." She sees hope in her mother's actions, since now she can foresee her own emancipation from Babamukuru's rule. Five days later, Maiguru returns, much happier and refreshed.
Just before Tambu's Grade Seven examinations, nuns visit the mission school to recruit students to attend a Catholic convent school called Sacred Heart. To her surprise, Tambu is offered a generous scholarship to attend. However, Nyasha thinks she will be brainwashed by the nuns. Meanwhile, Babamukuru refuses to let Tambu go, thinking that she will go astray. Maiguru uses her newfound confidence to speak up for Tambu, pointing out that in the 1950s, when she went to school, "people were prejudiced against educated women," and argues that it is high time that things changed.
Babamukuru takes Tambu back to the homestead for Christmas alone, since Maiguru has refused to "spend another Christmas catering for a family of two dozen". Babamukuru commutes between the mission and the homestead for weeks, and sometimes brings Nyasha and Maiguru with him. Tambu eavesdrops on a conversation between Babamukuru and Jeremiah, in which Babamukuru reveals that he is going to allow Tambu to go to the convent school. Excited, Tambu discusses this development with her mother, who becomes visibly depressed at the prospect of losing her child again. She won't eat or do any work; and the new baby, Dambudzo, develops diarrhea. Jeremiah sends for Lucia, who forces her sister to get up, bathe, eat meat stew, and take care of her baby.
After the holidays, Tambu returns to the mission. Her old friends, Maidei and Jocelyn, are no longer kind to her and show resentment that she is leaving to go to a "white" convent school. Back at the house, Nyasha refuses to eat. After Babamukuru commands her to eat all the food on her plate, she gobbles it down quickly and then goes to the bathroom to vomit. She confesses to Tambu that after she leaves, "there won't be anyone to laugh with." She worries about facing her father alone. When it is time to go to Sacred Heart, Babamukuru, Maiguru, and Nyasha all drive Tambu to the convent. The building and grounds are impossibly beautiful and well groomed, but Babamukuru is clearly on edge upon seeing the entirely white student body. A nun shows them to the room where "the Africans" will be sleeping - there are six beds crammed into a space for four.
As the semester progresses, Tambu throws herself into her studies. She does not keep in good touch with Nyasha, though Nyasha writes her many letters. One letter in particular is very emotional, revealing that Nyasha does not get along with the girls at school or with her father. In the following letter, she informs Tambu that she has "embarked on a diet," and after that, her letters stop coming as regularly. Tambu is so busy with her new activities and school work that she barely notices. When Tambu returns to the mission for a night, she notices a definite change in Nyasha, who has "grown skeletal." She shovels food into her mouth and then vomits. While Babamukuru wants Tambu to return to the convent the next day, she feels she cannot leave her cousin in this state. She is right; that evening, Nyasha flies into a suicidal rage.
Babamukuru agrees to take Nyasha to a white psychiatrist in the city of Salisbury. Unfortunately, that psychiatrist claims that "Africans did not suffer in the way [he] ... described," and almost convinces Babamukuru to just take Nyasha home and punish her. Later, a second psychiatrist recognizes that Nyasha needs to be put in a clinic for several weeks for observation and recovery. While she is there, Babamukuru takes Tambu back to the homestead, where Ma'Shingayi is adamant that Nyasha is being killed by her "Englishness," and warns Tambu to watch out for it. Tambu tries to banish her suspicion, but the narrator acknowledges that it stays with her. She shares that as she gets older, "quietly, unobtrusively and extremely fitfully, something in my mind began to assert itself, to question things and refuse to be brainwashed, bringing me to this time when I can set down this story."
Tambu's nervous condition manifests itself when the time comes for her parents' wedding. "Whenever I thought about it... I suffered a horrible crawling over my skin, my chest contracted to a breathless tension and even my bowels threatened to let me know their opinion." She is angry and resentful of Babamukuru for insisting that event take place. She finds it demeaning, and feels like it casts a shadow of sin over her childhood, but she cannot stop it. For the first time, Tambu disobeys Babamukuru by not going to the wedding.
She starts to understand that "deep in the less accessible areas of my mind, although outwardly I would have hotly denied it, I was ashamed of what to me was a pervasive and enervating vagueness." She worries that she is weak and lets "guilt, so many razorsharp edges of it, slice away at me. My mother had been right: I was unnatural; I would not listen to my own parents, but I would listen to Babamukuru even when he told me to laugh at my parents. There was something unnatural about me." On one hand, she feels that she should worship Babamukuru because her father always has. His education makes him a powerful figure, and he offers Tambu a place in his world. However, Tambu cannot reconcile her growing feelings of disapproval.
Lucia uses her wiles to get herself away from the homestead with Jeremiah and Takesure. She is six months pregnant when she gets to the mission, with the declared purpose of helping her sister give birth. But she asks for a job and gets it, and eventually enrolls herself in Grade One classes so that she might have some education, as well. Lucia's change in fortune is due to the very outspokenness that she is so often scolded for - she serves as an older example for Nyasha and Tambu, as well as for Maiguru. Maiguru finally stands up to Babamukuru and tells him how unhappy she is. She even leaves the house to demonstrate her independence, but returns after a week. By showing her husband that she would leave changes the dynamic between them. Her sojourn gives her the power to convince Babamukuru to send Tambu to the convent school.
As Tambu becomes more empowered, her mother's nervous condition begins to consume her. She blames Babamukuru for Nhamo's death, and when he takes Tambu away, she becomes anxious for her daughter's life. When she learns Tambu will be going to a convent school with mostly white students, she becomes anxious that Tambu will be afflicted with the dangerous "Englishness." Her depression prevents her from eating, bathing, or taking care of her baby until Lucia comes to the homestead and forces her out of bed. At the end of the novel, Tambu starts to understand the root of her mother's skepticism when Nyasha has a psychotic break.
The contrast between Nyasha and Tambu is at the core of Nervous Conditions. Dangarembga says, "whatever class and/or cultural difference there is between them, they still have to struggle with becoming a person given the common constraint of being a woman". Tambu comes from nothing, and therefore, is unable to question Babamukuru's authority. Nyasha, meanwhile, is bound by her privilege. She is worldly and yet, trapped in a society where she cannot express herself. Ultimately, her ideological incarceration drives her to the edge. Tambu, however, struggles to find her voice. Because an older Tambu is narrating the book, she can offer mature insight into her adolescent turmoil.