We begin in New Mexico, 1898. The dominance of steam power is about to come to an end. Oil is the future. Prospecting for gold and silver during this time is very, very hard work with the chance for a very, very unlikely payoff. Daniel Plainview is one of those young prospectors toiling in the wilderness for a chance at riches. He finds signs of precious minerals but breaks his leg in a dynamite accident and painfully climbs back to the surface. Practically dragging himself into town, he receives the paperwork establishing his claim.
Four years later Plainview discovers oil and swiftly changes direction, establishing a very small drilling company. However, not long after work begins a worker is killed by an equipment malfunction, orphaning the man’s infant son. Daniel adopts the boy as his own son: H.W. Plainview, who also becomes his business partner so that Daniel can assert his status as a family man when calling upon potential investors.
By 1911, H.W. is accompanying his father whenever Daniel attempts to buy drilling rights from various townsfolk. One night, a young man named Paul Sunday appears with the promise of a huge deposit of oil sitting beneath his family’s land. Daniel pays Paul and learns the deposit is located on the Sunday family farm in Little Boston, California.
Daniel and H.W. arrive at the Sunday farm, discovering that Paul has an identical twin brother named Eli who is the pastor of the town church. He is resistant to the price that Daniel is offering for the land and makes a demand for $10,000 which he tells Daniel will be going to his church. Daniel proceeds to buy up as much of the surrounding land he can get to maximize his control of the oil. Ultimately, there is just lone holdout: a man named William Bandy.
The town excitedly rallies around Plainview as his drilling operation brings money and jobs. H.W. develops a close friendship with Mary Sunday which will later blossom into romance and marriage. When H.W. informs his father that Mary’s dad sometimes beats her, Daniel even threatens the old man into putting an end to that practice. The drilling is successful and the flow of oil starts, but one of the workers is killed by an accident soon after.
A gas blowout deafens H.W. and starts a massive fire, destroying the oil derrick and halting extraction. Eli comes to view the problems associated with the drilling as signs that God is unhappy with Daniel for breaking his promise to allow Eli to properly bless the well. When he approaches Daniels with a demand for the $5,000 he is still owed, Daniel instead beats and humiliates him. Back at home, a bruised Eli berates and assaults his father for trusting Daniel in the first place.
One day, a stranger shows up at Daniel’s home claiming that he is Daniel’s half-brother, Henry. Although Daniel remains suspicious, he gives Henry a job and eventually the two grow closer. H.W., troubled by the loss of his hearing and the appearance of a rival for the affections of Daniel, sets their home on fire. An enraged Daniel sends his son away to a special school for deaf children in San Francisco. Although he pretends to accompany H.W. on the train, he winds up leaving the boy to make the trip with Daniel’s confidant Fletcher.
Daniel’s success has not gone unnoticed by the larger oil interests. H.M. Tilford, representing John D. Rockefeller’s Standard Oil in his attempts to create a total monopoly for himself, arrives with an offer to buy Daniel out. Daniel instead makes a deal with rival Union Oil to build a pipeline to pump the oil from his well to the coast. This turns out to be more difficult than he assumed, however, because the hypothetical pipeline would have to go through the Bandy tract, which Daniel had failed to purchase.
Meanwhile, Daniel is becoming more and more suspicious about Henry’s backstory. At gunpoint outside near the Bandy tract one night, Henry is forced to admit that Daniel’s actual half-brother Henry died of tuberculosis and that he took his place to find money and stability. He promises to go away and never come back, but Daniel is drunk on rage mixed with liquor, and kills and buries the imposter.
Daniel is awakened the following morning by Bandy, who had witnessed the entire scene and blackmails Daniel into going to Eli’s church to repent his sins and beg for forgiveness.
Daniel submits to being baptized and forced into admitting he abandoned his son by Eli as payment for the humiliation he received from Daniel earlier. However, Bandy does give permission for Daniel to build the pipeline on his property. From that point forward, Daniel becomes increasingly isolated and dependent upon alcohol. Even his reunion with H.W. when he returns from San Francisco does little to alleviate his unhappiness, control his greed or stop his descent into alcoholism. The pipeline is completed and Eli leaves town for missionary work.
In 1927, H.W. and Mary Sunday marry each other. Daniel has become a reclusive drunk holed up inside a lonely mansion. H.W. uses the assistance of a deaf interpreter to formally request that Daniel dissolve their legal partnership because he now has plans for his own company operating out of Mexico. A dissolute Daniel responds with contemptuous scorn for H.W.’s disability and then proceeds to mock H.W. by revealing H.W. was an orphan. H.W. leaves, by telling Daniel that he is happy to learn that Daniel’s blood does not run through his veins.
Some time later, a drunken Daniel receives a visit from Eli down in his private bowling alley. Eli informs him that he has expanded his ministry to radio but has fallen into financial difficulty. He offers to sell Daniel the Bandy tract so that they can drill for more oil. Daniel agrees, on the condition that Eli renounce his Christian faith as loudly as he can, shouting it to the rafters inside the bowling alley. With great reluctance and difficulty at overcoming his pride, Eli agrees and proceeds to shout out that he is a false prophet and that God is just a superstition.
Daniel then reveals that he has already drained the oil from the Bandy tract using directional drilling from nearby wells. He mocks Eli, telling him that Paul was the smarter of the two brothers and chasing him around the bowling alley. He attacks Eli with bowling balls and pins, finally smashing Eli’s head in and killing him.
Daniel’s butler comes downstairs to see what has happened. Daniel very nonchalantly tells him “I’m finished” and the film cuts to the end credits.
