A driven and ruthless oil prospector, Daniel Plainview, travels across California at the turn of the 20th century on a relentless quest to acquire valuable land and expand his oil empire. Along with his young, adopted son, H.W., who helps him garner trust and sympathy, he uses information from a local man, Paul Sunday, to purchase the oil-rich land in Little Boston, California, under the guise of developing a community. Plainview's ambition is matched by his skill in manipulating and coercing landowners to sell him their property at minimal cost, under the promise of wealth and prosperity.

As Plainview's fortune grows, so does the intensity of his conflicts with others, including his strained relationship with H.W. and his confrontations with Eli Sunday, Paul's twin brother and a fervent, opportunistic preacher in the local church. The tension between capitalism and religion becomes a central theme as Plainview and Eli battle for influence over the community. Each driven by their own version of faith—Plainview's in oil and wealth, Eli's in spiritual salvation—their rivalry escalates, reflecting the larger forces at play in the burgeoning American oil industry, where deception, ambition, and greed reach a boiling point, setting the stage for profound consequences for all involved.