Doña Bárbara by Rómulo Gallegos centers around a feudal relationship surrounding the Altamira Ranch and the two heirs who own it. Doña Bárbara is a main character in the story. She is the mestiza mistress of Lorenzo Barqueros and takes over his half of the ranch. She is a determined character, as she tries to expand the boundaries of the ranch by taking over the second ranch of Altamira. Santos Luzardo is the offspring and male heir to the second half of Altamira ranch. He was raised in Caracas with his mother and returns to the land when he decides to sell it. Upon discovering the situation with Doña Bárbara and the disarray the land has fallen into, he realizes he must try to get the ranch back and properly care for the land.

First, Luzardo makes peace with the Barqueros and squashes an old feud between both family names. He then takes the appropriate measures through the legal system to begin disputing the lost parts of the ranch. In a twist of events, Doña Bárbara and Santos Luzardo are able to reach a middle ground in determining the boundaries of their ranches. The surprising civility of the meeting is determined to be a result of Doña Bárbara's secret admiration and love for Santos Luzardo. Matters are further complicated when Marisela, Doña Bárbaras' daughter, also falls in love with him.

In the midst of making preparations to begin financing the fence building around his property, Luzardo is thwarted by Doña Bárbara's rogue henchmen. As things begin escalating to murder and violence, Doña Bárbara is torn between her love for Luzardo and her longing for ownership and power. She ultimately disposes of her trusted henchmen and is deserted by the rest of her crew. As she becomes aware of her daughter's love for Luzardo, Doña Bárbara disappears. She leaves a deed that transfers her land ownership to Marisela, provides the money for the fence, and returns the land she had taken over back to Luzardo. In the end, the marriage between Luzardo and Marisela combines the two ranches, and the history of the family feud is forgotten.

The Altamira ranch is a vast estate in the wildest section of the Arauca River basin of Venezuela, a ranch that was established early in the history of the country’s cattle business. Late in the nineteenth century, it was divided into two parts by one of the owners’ joint heirs. One part of the ranch kept the old name and went to the male heir of the Luzardo family. The other part went to a daughter who married a Barquero, and it took on the name from the new owner. As the years went by, the two families carried on a feud that killed most of the men on both sides. During the Spanish-American War, the owner of Altamira quarreled with his elder son and killed him; he then starved himself to death. His wife, Doña Luzardo, took her only remaining son to Caracas to rear him in a more civilized atmosphere.

Years go by. Finally the son, Santos Luzardo, decides to sell the ranch, which was allowed to deteriorate under irresponsible overseers. The young man goes into the back country to see the place for himself and to determine what it might be worth. On his arrival, he finds that the neighboring ranch of the Barqueros fell into the hands of Doña Bárbara, a mestiza who was the mistress of the real owner before she ran him off his property. Doña Bárbara is in the process of taking over the Altamira ranch as well, with the help of several henchmen, including Don Balbino, the ranch’s overseer. Santos decides to keep the ranch and try to make it prosperous again.

Santos is able to rely on the help of a handful of loyal cowboys who knew him as a child. These include Antonio, a cowboy who was his playmate years before. Santos’s first move is to end the feud between himself and the Barqueros. He finds Lorenzo Barquero living in a cabin in a swamp, the only land his mistress did not take from him. After making his peace with Lorenzo and his illegitimate daughter, Marisela, Santos takes them to live at Altamira ranch. Marisela is as beautiful as her mother, Doña Bárbara, and Santos wishes to retrieve her from barbarity.

Most of the cattle was stolen from the Altamira ranch, and only about one hundred head are left. Nevertheless, Antonio sees to it that many hundreds more are allowed to stray into wild country, thus saving them from Doña Bárbara and Señor Danger, an American squatter who is in the process of carving his own ranch out of Altamira land. One of Santos’s first acts is to discharge Don Balbino, Altamira’s treacherous overseer, who, since he is working for Doña Bárbara and is her lover, thereupon seeks the mestiza’s protection.

Santos, who was trained as a lawyer, decides first to try legal means of repossessing the lost parts of his ranch. He goes to the local magistrate and, through his knowledge of the law, forces that official to call in Doña Bárbara and Señor Danger. They are told to permit a roundup of his cattle and to help him, since their herds are intermingled with those from Altamira. They are also told to build fences, since according to the law, they have too few cattle to let them run wild. Doña Bárbara is to help build a boundary fence between her ranch and Altamira. She accepts the decisions with surprisingly good grace. Her henchmen are amazed, for previously she rode roughshod over all opposition. The answer lies in the fact that she is secretly in love with Santos and hopes eventually to inspire his love (and acquire his property) by her beauty.

As the weeks of ranch routine pass, Santos is glad that he brought Marisela to his house, for his efforts to teach her culture keep him from losing touch with civilization. Although his interest in her is only that of a friend and tutor, Marisela falls in love with him.

Along the Arauca River are thousands of herons. When the birds molt, the people of Altamira go out to collect the valuable plumes; fifty pounds of the feathers are sent to market with two of the cowboys, and Santos intends to use the money from the sale to fence his boundaries. On their way to market, the cowboys are murdered and the feathers stolen. Their loss and the failure of the authorities to track down the culprit cause a great change in Santos. He determines to take the law into his own hands and when necessary to match violence with violence.

His first act is to have three of Doña Bárbara’s henchmen captured and sent to prison, for they were long wanted for a number of crimes. A short time later, he receives word from Doña Bárbara, who is torn between her love for him and her wish for power. She tells him that in a certain canyon he will find the thief who took the feathers. Santos goes there in the night and kills the Wizard, Doña Bárbara’s most trusted and bloodthirsty henchman.

By this time, Don Balbino, Doña Bárbara’s lover, becomes distasteful to her. She has him killed after discovering that it was he who stole the feathers, and, to aid Santos, she throws the blame of the Wizard’s murder on Don Balbino. Having recovered the feathers, Doña Bárbara goes to town to sell them for Santos. At the same time, she has documents made out to transfer the disputed lands to their rightful owner. When she returns to her ranch, she finds that her people deserted her; they cannot understand why she turned on her trusted killers. Doña Bárbara rides immediately to Altamira, where she finds Santos talking to Marisela, whose father recently died. Because the girl’s love for Santos shows plainly on her face, Doña Bárbara, unseen, draws her revolver to kill her daughter. Her own love for Santos prevents the deed, however, and she rides away without revealing her presence.

Doña Bárbara is not heard from again. The next day, a large envelope is delivered to Santos. In it, he finds a sheaf of documents returning the property she stole from him, and others transferring the Barquero ranch to Doña Bárbara’s daughter, Marisela. Shortly afterward, Santos and Marisela marry, and the two ranches that were separated for many years are once again joined under one owner.