When Blanca is about three years old, the family decides to spend a summer together in Tres Marias. The moment they arrive, Blanca meets Pedro Tercero Garcia, and they fall in love. Clara is incredibly happy in Tres Marias. For the first and only time in her life she becomes involved in earthly pursuits, devoting herself to teaching the workers and their families basic education, nutrition, and health care. She also tries to teach the women about gender inequality, but they realize that they cannot follow her advice. Esteban becomes enraged when he discovers her efforts with the women, but she simply ignores him and diffuses his anger.
At the end of the summer, Clara is so content in Tres Marias that they stay. Ferula is the only member of the family who is unhappy there. She begins to have nervous fits, but she refuses to leave because she does not want to be separated from Clara, the only person she ever truly loves in her life.
In the fall, an ant plague strikes Tres Marias. Esteban tries everything to rid the property of the ants, including bringing in Mr. Brown, a midget gringo "agricultural technician specializing in insecticides." After hearing that Mr. Brown's method will take months to succeed, too long a time to save Tres Marias, in desperation they go to Pedro Garcia, who successfully rids Tres Marias of the ants. Pedro Garcia shows them the way out—as he explains to Mr. Brown, all that was needed was to "[T]ell them to go, that they're a nuisance her. They understand."
At Tres Marias, Clara becomes pregnant again, and they must return to the city so that she can have access to appropriate medical attention. Clara has a difficult pregnancy during which she stops speaking. Esteban is not comfortable in the house in the city filled with women, but he feels that they need his male presence. Toward the end of her term, Clara begins speaking again to announce that she will have twins named Jaime and Nicolas. Esteban is furious that one of them will not be named after him, and in a rage he goes off to the best brothel in the city, the Christopher Columbus. There he re-encounters Transito Soto. Transito is happily working as an independent prostitute at the Christopher Columbus, with a reputation as the best woman they have. However, Transito still wants more independence. She and Esteban share not only great sexual appetites but also great ambition, and she tells him of her dream to open up a cooperative of "whores and fags".
A few days later, Severo and Nivea del Valle die in a car accident, in which Nivea's head is severed from her body. Everyone in the family tries to shelter Clara from the news because of her pregnancy. Clara finds out through her dreams and premonitions. Since rescuers were unable to locate Nivea's head, she is buried without it, another fact that everyone tries to hide from Clara. Clara also however knew about the severed head and is determined to find it. Ferula agrees to help her, and following Clara's instincts, they drive out to the location of the accident and recover the head, where hundreds of rescuers missed it. On the way home, Clara goes into labor and Ferula delivers the twin boys as soon as they arrive home. The two women do not tell anyone about having found Nivea's head, and they hide it in a hatbox. When They tell Esteban about it, he moves it to the basement.
Nana moves in with Clara and Esteban, and she and Ferula take care of the family, while Clara becomes intensely involved with the three Mora sisters and their eclectic group of spiritualist friends. She remains oblivious to the intense rivalry over her affection between Nana and Ferula, and much more importantly between Ferula and Esteban.
Over the years, "Ferula had come to love Clara with a jealous passion" while Esteban's "love for [Clara] had grown to the point where it had become an obsession." They enter into a rivalry which comes to a head when Esteban returns home from Tres Marias unexpectedly to find Ferula sleeping in Clara's bed. In a rage, he throws his sister out of the house; she leaves, cursing him to eternal loneliness. Clara makes a few attempts to find Ferula, but when she realizes that Ferula does not want to be found, she returns to devoting her time to her spiritualist activities and to raising Blanca as her mother raised her, while the twin boys are sent off to boarding school.
The family continues to return to Tres Marias at various intervals, during which Blanca and Pedro Tercero Garcia's love grows. Pedro Tercero Garcia also becomes increasingly involved in organizing for justice at Tres Marias. During this time, Pancha dies, leaving behind the son she and Esteban had together, as well as her grandson, also named Esteban Garcia.
Although it involves a great deal of serious social and political commentary, the plot of The House of the Spirits is driven by a series of romances: Esteban and Clara's, Blanca and Pedro Tercero's, Alba and Miguel's. Every great love affair and every marriage in The House of the Spirits is initiated on first sight at a very young age, although those involved often do not realize what is happening at the time. Blanca and Pedro Tercero are a prime example. Their love also represents the first great breach of class divisions in the novel.
The division between the big house on the corner and Tres Marias corresponds to the theme of culture versus nature or civilization versus barbarity. On Esteban's first trip to Tres Marias, it seems as if the divisions between each would be simple. Tres Marias was natural and uncivilized. While nature was bountiful and had restorative powers, it needed the influence of civilization in order to be productive in a useful manner. This trip to Tres Marias shows those divisions to be more complicated. It is only in Tres Marias that Clara becomes attentive to practical, productive detail, reversing the order of influence. While Pedro Tercero is described as a cannibal—the paragon of barbarism—his activity consists of playing with Blanca, while Esteban flies into wild destructive rages. The most striking moment of reversal, however, is the episode of the ants. The ants represent the destructive or barbaric side of nature. Esteban tries to get rid of the ants with all sorts of methods he brings in from "civilization." North America, or the gringos in the figure of Mr. Brown, represent the most extreme versions of civilization and progress, modernity, and science. Mr. Brown's method of removing the ants, however, while it may work takes too long. Pedro Garcia, an old peasant, is the only one who is able to cure the ant plague. He removes the ants in the most "natural" of means: singing and talking to them.
Esteban cannot tolerate Ferula's possible lesbianism, especially not when it may involve his own wife. Ferula's lesbianism is never confirmed or denied. Background suggestions of both lesbianism, in Ferula's case, and homosexuality, in the figure of the male prostitutes who work with Transito Soto, are found throughout the novel but are not a major theme. Esteban's violent reaction to finding Ferula in Clara's bed, however, has important lasting effects. The end of this chapter is in fact full if events that will attain great importance later. In addition to Ferula's curse, the communist teachings of Father Jose Dulce Maria, the figure of Esteban Garcia, and Pedro Tercero's song will re- appear. While many apparently unimportant details are signaled by the narrators as foreshadowing events to come, this is not always the case. The novel is also filled with details that have no lasting importance. The effect of the reappearance of some details with heightened importance later on puts an emphasis on detail in general, so that while the major romance plots continue, they diminish in relative importance.