New Mexico. It is 1898. The dominance of steam as the fuel that powers the engine of trade is about to come to an end. Those hardy souls risking their lives and savings and are gambling on the future of oil. Prospecting for gold and silver during this time is very, very hard work with the chance for a very, very low payoff. Daniel Plainview is one of those young prospectors and for the next half-hour, give or take, the reality of just how hard prospecting for minerals is reveal without a single word as Daniel proceeds to show how dangerous laying dynamite in the earth could be. He breaks his leg and painfully manages to make it to the surface on his own. Practically dragging himself into town, he receives the paperwork establishing his claim.
Four years later Plainview discovers oil beneath the ground and swiftly changes direction, establishing a very small drilling company. Prospecting for oil is just as dangerous as mining for precious minerals and one of the workers falls to his death inside the deep hole being drilled into. The death means that the man’s young son has just become a total orphan. Daniel adopts the boy as his own son: H.W. Plainview also becomes his business partner since his stature confirms Daniel’s status as a family man when calling upon potential investors who themselves, for the most, struggling families.
By 1911, H.W. has grown into a fine young boy and appears right alongside his father when Daniel shows up in town to announce plans to drill. One night, a lone young man named Paul Sunday seems to appear from out of nowhere with the promise of a huge deposit of oil sitting beneath his family’s land. When Daniel tries find out where this property is located, Paul proves to be more clever than he looks as he gives nothing away.
When Daniel and H.W. later show up on the Sunday farm, they discover 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 and makes a demand for $10,000 which he tells Daniel will be going to his church. The Sunday property represents just the beginning of Daniel’s concerted effort to accumulate all the tracts in the area deemed applicable to the process of getting and delivering the oil. Ultimately, there will be just lone holdout: a man named William Bandy.
The town excitedly rallies around Plainview as his drilling operation brings money and jobs. Everything is going along well. H.W. develops a close friendship with Mary Sunday which will blossom into romance and marriage. When he informs his father that Mary’s dad sometimes beats, he even manipulates the old man into putting an end to that practice. The drilling is successful and the flow of oil starts, but eventually the operation will cost one man his life and H.W. Plainview his hearing.
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, he is shocked when he is instead beaten and humiliated by the oil man. Back at home, a bruised Eli attacks his father for being stupid enough to trust Daniel in the first place.
One day, a strange 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 a little closer. H.W., troubled by the loss of his hearing and the appearance of a rival for the affections of Daniel, sets the home on fire with the intent of getting rid of Henry for good. An enraged Daniel sends his son away to a special school for deaf children in San Francisco. Although he seems like he intends to accompany H.W. on the train, he winds up leaving the boy to make the trip by himself.
Daniel’s success has not gone unnoticed by the larger oil interests. Men representing John D. Rockefeller’s Standard Oil in his attempts to create a total monopoly for himself shows up with an offer to buy Daniel out. Daniel instead makes a deal with rival Union Oil to pump the oil from his well to the coast. This turns out to be more difficult than he assumed, however, because there is a major obstruction to this plan: the Bandy property which he was never able to purchase.
Meanwhile, Daniel is becoming more and more suspicious about Henry’s story of being his relation. At gunpoint outside near the Bandy tract one night, Henry is forced to admit that Daniel’s actual half-brother Henry died of consumption and he took his place thinking he could make a little money. 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 witnessed the entire scene taking place between Daniel and the imposter and blackmails Daniel into going to Eli’s church to repent his sins and beg for forgiveness.
Daniel submits to being baptized, beaten, humiliated and forced into admitting he is a bad father become he abandoned his son by Eli as payment for the humiliation he received from Daniel earlier. From that point forward, Daniel becomes increasingly more 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. Even Eli’s decision to leave town in pursuit of missionary work fails to change his outlook.
By 1927, H.W. and Mary Sunday are old enough to marry. Daniel has essentially 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. disability and then proceeds to finally confess that H.W. is not even his real son, but an orphan. H.W. leaves by telling Daniel how grateful he is 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 taken his ministry to the airwaves and preaches the gospel over the radio. He has come with an offer: ownership of the Bandy tract. Bandy has recently passed away and Daniel shows interest but he will agree to the deal only if one unalterable term of condition is met: Eli must denounce his 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 God is just a superstition.
Daniel then proceeds to take this humiliation to a level Eli never thought possible. He informs Eli that the property he is trying to sell is utterly worthless at any price. Face with the impossibility of convincing Bandy to sell and the untenable prospect of the impact that would have on his plans to send his oil by pipeline to the coast, he instead chose the only alternative left. He surreptitiously drained all the oil belonging to the Bandy property through existing wells, thus sucking the Bandy estate dry.
Now desperate, Eli is forced to admit his own truth: he is not the successful radio preacher he claims. He is, in fact, facing ruin as a result of a recent panic in the national economic. He furthermore confesses to having reach this lowly state because he gave in to flesh desires and allowed the devil to tempt him. Daniel then ramps things up even further by telling him that his brother Paul is the real chosen one, not him. Dazed, Eli can only extend the offer to sell the Bandy estate again.
Daniel explains again how he has nothing to offer because there is nothing left by using the example of Eli having a milkshake and Daniel having a milkshake, but Daniel having a straw that can reach all the way across the Eli’s milkshake then soon Eli no longer has a milkshake at all because he used his straw to drink it all up. He reminds Eli that he once told him he would eat him and then tells that God won’t save him because God doesn’t save idiots.
Eli, sniveling and beyond words and even comprehension at this point, can only try to get away from a Daniel who is obviously one step away from madness. Daniel chases after him and attacks. Finally, he picks up an errant bowling pin and smashes it with all his might down onto Eli’s head before falling over to the side.
The shouting and the commotion has brought Daniel’s butler into the bowling alley to see what’s going on. Daniel very nonchalantly tells him “I’m finished.”