In 1898, Daniel Plainview is a silver prospector mining a potentially precious ore vein from a pit mine hole in New Mexico. In the process of dynamiting the lode, he falls and breaks his leg. He saves a silver sample, climbs out of the mine and drags himself to an assay office, where he receives a silver and gold certificate claim. In 1902, he discovers oil near Los Angeles and establishes a drilling company. Following the death of a worker in an accident, Daniel adopts the man’s orphaned son. The boy, H. W., becomes his nominal business partner, allowing Daniel to present himself to potential investors as a family man.
In 1911, Daniel is approached by Paul Sunday, a young man who tells him of an oil deposit under his family’s property in Little Boston, California. Daniel attempts to purchase the farm from the Sundays at a bargain price, but he is blocked by Eli, Paul’s twin brother and a local evangelical preacher. In exchange for the rights to the property, Eli demands $10,000 “for his church.” An agreement is made and Daniel acquires all the available land in and around the Sunday property, save for one holdout: William Bandy.
Oil drilling commences, but soon a series of misfortunes occur: an accident kills one worker and a gas blowout deafens H. W. Eli blames the disasters on the well not being properly blessed. When Eli publicly demands the money still owed to him, Daniel beats and humiliates him. At the dinner table that night, Eli attacks and berates his father for trusting Daniel.
A man arrives at Daniel’s doorstep claiming to be his half-brother, Henry. Daniel hires Henry and the two grow close. A jealous H. W. sets fire to their house, intending to kill Henry. A furious Daniel sends H. W. away to a school for the deaf in San Francisco. A representative from Standard Oil offers to buy out Daniel’s local interests, but after a perceived slight, Daniel refuses and strikes a deal with Union Oil to build a pipeline to the California coast. However, Bandy’s ranch remains an impediment.
Reminiscing about his childhood, Daniel becomes suspicious to the truth of Henry’s story and confronts him one night at gunpoint. “Henry” confesses that he was a friend of the real Henry, who died of tuberculosis, and that he impersonated Henry in hopes of gaining employment with Daniel. In a fit of rage, Daniel murders the impostor and buries his body.
The next morning, Daniel is awakened by Bandy, who knows of Daniel’s crime and wants Daniel to publicly repent in Eli’s church in exchange for the pipeline construction rights on his land. As part of his baptism, Eli humiliates Daniel and coerces him into confessing that he abandoned his son. Some time later, as the pipeline is under construction, H. W. is reunited with Daniel and Eli leaves Little Boston for missionary work.
In 1927, H. W. marries Mary Sunday, the younger sister of Paul and Eli. He visits Daniel, who is now an extremely wealthy but alcoholic recluse in a large mansion. Through a sign language interpreter, H. W. asks his father to dissolve their partnership so that he can establish his own independent drilling company in Mexico. Daniel reacts brutally, mocking H. W.’s deafness before revealing his true origins as an orphan “bastard from a basket.” H. W. tells Daniel he is glad that they are not related and storms out.
Eli visits Daniel, who is drunk in his private bowling alley. Eli, now a radio preacher, offers to sell Daniel the property rights to the Bandy ranch, as William Bandy has recently died. Daniel agrees on the condition that Eli denounce his faith and his own credibility. Eli reluctantly acquiesces, only for Daniel to then reveal that the property is now worthless because he has already drained its oil by slant drilling from neighboring wells. Shaken, Eli confesses to being in dire financial straits and to having strayed morally. Daniel taunts Eli in revenge for his own previous humiliation before chasing him around the bowling alley and eventually beats him to death with a bowling pin. Exhausted, Daniel collapses on the floor next to Eli’s body and announces that he is “finished.”