West Texas in June 1980 presents a barren landscape, where Sheriff Ed Tom Bell (Tommy Lee Jones) grapples with the escalating violence that shadows his family's legacy in law enforcement. Llewelyn Moss (Josh Brolin), while hunting pronghorn, stumbles upon the aftermath of a disastrous drug deal. The sight is gruesome: several dead men, some dogs, a gravely injured Mexican pleading for water, and a satchel containing two million dollars, which he takes to his trailer. That fateful night, as he returns later with water for the wounded man, he is startled by two men in a truck, leading to the loss of his vehicle. With his intimate knowledge of the terrain, Moss manages to evade his pursuers.
Upon returning home, he quickly hides the cash in the air vent of his motel room after sending his wife Carla Jean (Kelly Macdonald) to her mother's for safety. Meanwhile, Anton Chigurh (Javier Bardem), a remorseless hitman, is on the hunt for the stolen money. He's already left a trail of horror, including the murder of a sheriff's deputy, which facilitated his escape. Chigurh’s chilling method involves a coin toss, offering his victims a chance at survival based on chance.
As Bell investigates the ensuing violence, Chigurh discovers Moss's abandoned truck at the drug deal site. Tasked with reclaiming the money, he is handed a tracking device by the buyers and swiftly eliminates them before zeroing in on Moss. After Chigurh breaks into Moss's hideout, he ambushes a group of Mexicans intending to confront Moss, but the hunter remains one step ahead. Chigurh’s attempt to find Moss in a hotel culminates in a violent standoff, leaving both men injured. Moss manages to hide the satchel near the border but is ultimately taken to a Mexican hospital, desperate and battered.
In the meantime, the resourceful Carson Wells (Woody Harrelson), another hired gun aiming to stop Chigurh, approaches Moss with an offer of protection. Back home, Bell warns Carla Jean of the imminent danger, advising her to keep in touch so he can lend protection to her husband.
Chigurh's ruthlessness continues as he ambushes and kills Wells before he can assist Moss, further complicating matters when he tauntingly answers Moss's call from Wells's phone, promising safety for Carla Jean in exchange for the money. Refusing to be swayed, Moss attempts to make arrangements with Carla Jean but is thwarted by fate when armed men confront him at a motel, leading to his eventual demise.
Bell's arrival at the scene reveals Chigurh's methodical brutality, as he discovers that the vent cover has been removed, indicating Moss's unsuccessful tactics for hiding the money. Following the chaos, Bell confides in his Uncle Ellis (Barry Corbin), contemplating retirement as he feels ill-equipped to handle the monstrous reality of their world.
As tragedies unfold, Carla Jean, returning from her mother's funeral, faces Chigurh. He offers her a dire choice through a coin toss, but she challenges him, stating the power lies with him. The open-ended fate leaves Chigurh to depart alone, a chilling implication suggesting he has taken her life. Finally, now retired, Bell shares symbolic dreams with his wife (Tess Harper)—one about losing a treasured gift from his father, and another where he and his father traverse a snowy pass, hinting at a reunion in the afterlife that he longs for.
