In 1898 California, taciturn prospector Daniel Plainview strikes a small vein of silver in a pit mine but badly injures his leg in a fall. Four years later, as Daniel oversees construction of an oil well in Coyote Hills, an accident results in the death of one of his workers. Daniel adopts and lavishes affection on the man’s orphaned baby, whom he names HW. By 1911, Daniel has become prosperous from his Coyote Hills oil strike but desires to enrich himself further by buying oil leases from small communities. Bringing HW, whom he calls his partner, with him, he proclaims himself an oilman and a family man, who will give the local landowners one-sixth of the profits from the wells. One night, while overseeing a new oil field in Signal Hill, Daniel and his right-hand man, Fletcher Hamilton, are approached by teenager Paul Sunday, who offers to reveal the whereabouts of a rich, untapped oilfield for a $500 finder's fee. After Daniel reluctantly agrees to the terms, Paul shows him a map of an area surrounding his family's goat ranch in Little Boston, near Central California land parcels being bought by Standard Oil. A short time later, Daniel and HW travel to Little Boston and tell Paul's father Abel that they are hunting quail and would like permission to camp on his land. Later, when HW steps in some seeping oil, he rushes to show his father, who laughs with his son over the find. That night, as Daniel and HW eat dinner with the Sunday family, Daniel offers Abel $3,700 for his land. The fervently religious Abel thanks God for the offer, but his son Eli, a preacher, accuses Daniel of deception and demands a $10,000 bonus and a new road to his church. Daniel warily agrees to Eli's terms and soon, with the assistance of Al Rose, the local real estate agent, he is buying up as much local land as possible. Hoping to outmaneuver Standard Oil and avoid railroad transportation fees set by the company, Daniel plans to build a pipeline to the nearby coast and strike a deal with their competitor, Union Oil. As men begin to pour into the burgeoning oilfield, Eli, a charismatic faith healer, tries to convert some of the men to his Church of the Third Revelation. The day before the first derrick is to be dedicated, Eli goes to Daniel to say that he should be allowed to bless the well at a small ceremony marking the occasion. Daniel agrees, but the next day, after naming the well for Eli’s sister Mary, Daniel himself recites a blessing, leaving Eli stunned and angry. One night, after workman Joe Gunda dies in an accident, Daniel asks Eli to oversee the religious Gunda's funeral. Eli tells Daniel that Gunda died because the well was not blessed, but Daniel simply laughs, saying that Eli's faith-healing, which he witnessed at the church, was "a goddamn hell of a show." Some time later, as the third oil well is being drilled, a gusher bursts up, causing HW, who had been watching from above, to lose his hearing from the force of the eruption. A distraught Daniel rushes to his son and carries him back to their cabin, but quickly leaves to cap the well. One day, when Eli goes to Daniel to demand his $10,000, Daniel becomes enraged, screaming that Eli is a faith healer, yet his son cannot hear. He then beats and humiliates Eli, throwing him onto the ground and smearing his face with muddy oil. That night, Eli lashes out at Abel, calling him and the absent Paul lazy and stupid, then mercilessly beats him. Some time later, a man approaches Daniel’s cabin and says that he is his brother from another mother. Daniel is wary at first, but when the man, whose name is Henry, reveals details about Daniel’s family in Fond du Lac, Wisconsin, Daniel accepts him. Henry says that he is not interested in wealth, but merely hopes to have a job, at which he will work hard. That night, HW, who has sunk into depression over his hearing loss and his father's coldness, sets fire to the cabin, but Henry awakens in time to save Daniel. Knowing that HW is responsible, he chases after the fleeing boy and brings him back to the cabin. Some time later, after finding a school for HW, Daniel takes the boy onto the train and gently holds him, then leaves and sends in Fletcher. The boy screams for his father, but Daniel walks away as the train leaves the station. Weeks later, Daniel takes Henry with him to a meeting with Standard Oil executive H. M. Tilford and others who offer to buy Daniel's Coyote Hills property. Although he readily agrees to sell Coyote Hills, he refuses their offer of $1,000,000 for the Little Boston field and erupts into a violent rage, threatening to cut Tilford’s throat for suggesting that he should take the money and spend time with his boy. Soon Daniel learns from Al that his pipeline cannot go through the shortest route to the sea because Daniel never acquired the rights from Bandy, the one holdout among the local landowners. With Henry, Daniel travels to the Bandy farm, but is told by William Bandy that his grandfather is away. Daniel and Henry then take a swim in the ocean and relax on the shore. When a casual remark about their hometown does not elicit the expected response from Henry, Daniel deduces that he is a fraud. That night at their campsite, Daniel confronts Henry, who reveals that he became a close friend of Daniel’s real half-brother, who died of tuberculosis some months before. Henry adds that he acquired enough knowledge to impersonate the brother by reading through his diary. Daniel, who has told Henry that he learned to hate little-by-little and finds nothing to like in humanity, then places his gun to Henry's temple and shoots him. After burying Henry's body, Daniel weeps while reading through the diary and finding a baby picture within the pages. The next morning, Daniel is awakened by Bandy, who calmly tells him that he may use his land for the pipeline, but only if he is washed in the blood of Jesus to atone for his sins. Daniel laughs, but when Bandy shows him the gun used to kill Henry, he agrees. At the church, Daniel reluctantly comes forward to be baptized by Eli, who shouts of casting out the devil as he repeatedly slaps Daniel. Although emotionally overwrought during the baptism, Daniel calmly leaves the church to finish his pipeline. Some time later, as Eli departs on the train to start a new ministry in other oilfields, HW returns with a signing interpreter. Daniel embraces the still deaf boy and whispers “I love you” into his ear, then shows him the pipeline. That evening, sitting in a restaurant waiting for their meal, Daniel seethes when Tilford and his colleagues are seated at the next table. Although the men try to ignore Daniel's loud comments about his deal with Union Oil, he makes a scene. As the months pass, HW becomes more proficient in signing, as does Mary, his close companion. In 1927, a now grown HW and Mary wed in a Catholic Church. When HW goes to his father's palatial mansion to tell him that he loves him but wants to go to Mexico to start his own, small oil company, Daniel lashes out, cruelly referring to him and his interpreter as "hand flappers" and revealing that HW is not his real son. After he calls HW nothing more than a "bastard in a basket" who has nothing of himself in him, HW leaves, saying that he is glad he has nothing of Daniel in him. One night, Eli goes to see Daniel, who has fallen into a drunken stupor in the mansion's bowling alley. Well-dressed and sporting a jewel-encrusted cross, Eli cheerfully drinks with Daniel. Relating that old Bandy has died and that William, who desires to be an actor in Hollywood, wants to sell his land, Eli asks for a $100,000 broker's fee for the sale. After forcing Eli to proclaim that he is a false prophet and that God is a superstition, Daniel loudly boasts that he no longer needs Bandy's land because he has drained its oil from his own properties, which surround it. Now unnerved, Eli breaks down and admits that he needs the money because of losses in the stock market and the costs of his vices. Daniel then gleefully reveals that Paul received the $10,000 finder's fee, enabling him to start his own small oil business, which brings him $5,000 a week. As Eli becomes increasingly hysterical over Daniel's rebukes, Daniel starts to throw bowling balls at him. Then, when Eli falls, Daniel beats him to death with a bowling pin. Having been awakened by loud noises emanating from the bowling alley, one of the servants calls after Daniel, who shouts "I'm finished."