Grant, Biscuit, and Milo are punks living in Queens who crave something more than their everyday lives. They decide to move to Los Angeles and set out on a cross-country drive, chasing a wilder fate beyond the city limits. In Utah they come across an Elvis impersonator, Daredelvis, and lend a hand to get his trailer unstuck, a small act that pulls them into a series of odd, detuned encounters. During a desolate night, Grant spots a mirage of a cowboy on horseback, a vision that will quietly haunt their journey.
Their highway tale turns grim in the Arizona desert when a gang of vicious rednecks descends on them. The gang’s leader, Missoula, attacks with brutal certainty and murders Milo, leaving Grant and Biscuit to scramble for survival under a sky of dust and doubt. The pair manage to escape the attack and collapse in the desert, where Grant is again visited by the mysterious cowboy, a recurring figure that seems to guide, tempt, and challenge him.
Back home, the sheriffs are skeptical and fail to corroborate their story—no record of Missoula or his gang and Milo’s body remains missing. Undeterred, Grant resolves to track down the gang to avenge Milo’s death, even as Biscuit warns against chasing a phantom. Their search leads them back into Utah, where they discover one of the gang’s trucks overturned and several members dead. Before dying, a member hints that Missoula is moving north toward Montana, and the search leads them to meet Jessie, a young woman who runs a gas station and towing business.
A brutal pursuit follows as Grant and Biscuit locate Missoula’s truck and engage in a high-speed shootout with Missoula and his partner, Blix. The duo crash in the desert, and Jessie arrives, rescuing them and teaching Grant how to shoot and ride. A tender bond forms between Grant and Jessie, and Biscuit’s head fills with a dreamlike memory: a Native American tribe slaughtered by Union soldiers led by Missoula. Waking from the vision, Biscuit begins to imitate a Native American warrior, insisting they press on. Jessie outfits the two in exaggerated Western costumes and lends them a battered 1959 Buick Invicta, complete with bull’s horns on the hood, signaling a playful, yet perilous leap into the wild.
In Wyoming, the boys track Daredelvis to a rodeo and recruit him to aid in capturing Wes, from whom Milo’s stolen jacket has resurfaced. Wes is killed by a bull before he can reveal Missoula’s whereabouts, and the trio press on toward a ghost town rumored to be Missoula’s hideout. Grant again sees the cowboy in the distance, while Biscuit interprets the vision as a sign to press deeper into the past. The town proves empty, and the pair drink away their fear, slipping into a dreamlike sequence in which the cowboy Witherspoon appears with a trio of Native American warriors. Witherspoon performs a magic act, transporting Grant back in time to the town’s bustling heyday, while Biscuit is sent back to participate in a tribal gathering.
They awaken hung over but with a clue—a matchbook found in Milo’s jacket—that leads them to a saloon in a Montana town. There, they spy Missoula and Blix and trail them into a movie theater. A firefight erupts, but Grant hesitates, and Missoula and Blix manage to escape while Grant and Biscuit are arrested. The duo are jailed, and Missoula and Blix murder two sheriff’s deputies and assault the jail to finish the job. Jessie arrives at the last moment to spring them free. A climactic duel unfolds: Grant shoots Blix and wounds Missoula, then pursues Missoula to an abandoned building and tackles him off a high ledge. Missoula fires a final shot, hitting Grant in the arm, but Grant answers with a fatal blast, killing Missoula. As the dust settles, Witherspoon and the Native American warriors, now joined by Milo, ride off into the distance, leaving Biscuit and Jessie to arrive on the scene and witness the fading silhouettes.
