Three recent graduates, James, Day, and Fisher, are picked up by their friend Tyler, whom they haven’t seen for a year. Tyler drives them down a forested road, and the group trades ideas about which animals would win in a fight as they chat and joke along the way. The turnoff Tyler hopes to reach remains elusive, and when he turns the car around, a thick wall of trees suddenly blocks the road. After Tyler steps out to investigate, a swarm of frantic people bursts from the forest, pleading to be let in. The four manage to push the car forward, but Fisher’s arm is clawed during the chaos. They pause briefly to tend to the wound, only for the vehicle to be swarmed again. As they struggle to understand their bizarre predicament, they realize the road seems to stretch endlessly, with no clear end in sight.
They push through the night, and James notices the fuel gauge hasn’t budged. Tyler surmises that the engine isn’t supposed to function properly and that they should not switch off the ignition. The trio drives for a full day, taking turns at the wheel, and they begin to notice an odd lack of fatigue or hunger; even Fisher’s arm seems to heal before their eyes. They start to theorize about why they are trapped on this interminable roadway. Using timers on their phones, they conclude there’s a 90-second window after stopping before the car is attacked again. Tyler wanders into the woods and finds it continues without end, and the people around him appear docile within.
Inside the car, they inventory supplies, noting a Clif Bar among the items, and James cautions against eating it. Frustration grows, and Tyler and James restrain and question a man they pull from the forest, but the man does not respond. They eventually discover an abandoned car parked on the opposite side of the road, its keys missing and the odometer reading maxed out at 999,999 miles.
After more than 50,000 miles of driving, Tyler concedes defeat and stays behind in the forest as the others continue ahead. Time passes, and the remaining three adapt to the monotony, scavenging from abandoned vehicles to amuse themselves while maintaining a rhythm of similar conversations and rest stops. Day and Fisher begin daily screaming sessions to vent their frustration, something James does not participate in. Day and Fisher settle into the routine more readily than James, who remains fixated on finding a way out. One day, while inspecting another abandoned car, they notice that no one is emerging from the woods anymore. James feels a spark of hope, but Fisher and Day are less enthused.
At 835,000 miles, Day removes the keys from the ignition, and the two tell James that there is no escape and that he is torturing himself with hope by continuing to drive. In a tense struggle over the ignition, James wrests the keys from Fisher; he tries to restart the engine, and, after a moment of seeming failure, a prayerful plea is followed by the engine finally turning over. James drives off, leaving Day and Fisher behind. Left alone on the road, the two share a quiet, uneasy embrace.
When the odometer passes 1,100,000 miles, it begins to rain, adding to James’s unease. He continues driving and eventually comes across dozens of abandoned cars lining the road. He ventures on foot past the vehicles and reaches the end: a circular strip of asphalt surrounded by cars from different eras, with a single sign that reads, “ROAD ENDS.” James sits at the edge of the circle for a long time before returning to the car, consuming the Clif Bar, and crying. He then unleashes another loud screaming session outside the vehicle before climbing back in and resuming the journey down the endless road. Later, James encounters another empty vehicle and drags a lethargic man off the roadside into the car. As he drives, the now-responsive man joins in a discussion about which animals would win in a fight.
