A young, bearded drifter named Rambo stands hitchhiking at a gas station on the outskirts of Madison, Kentucky, when Police Chief Wilfred Teasle picks him up, not to offer a ride, but to escort him out of town. Teasle is troubled by Rambo's appearance: mud-crusted boots, rumpled jeans, a blood-speckled sweatshirt, and long hair. Rambo recognizes a familiar pattern: Police in 15 other towns have driven him away for how he looks. He resolves not to be pushed. When Teasle drops him past the town limits, Rambo turns around and walks back.
Teasle catches Rambo at a diner and drives him out a second time. Rambo eats his hamburgers in a ditch, burns the wrappers from combat habit, and walks back into town. He is a Vietnam veteran and former Green Beret. When Teasle confronts him on a bridge and rests a hand on his holstered pistol, Rambo considers how easily he could kill the man but controls himself. He agrees to get in the cruiser, warning he will just return again.
At the police station, Rambo refuses to give his name or produce identification. A strip search reveals a bullet scar, knife scars across Rambo's chest, and dozens of lash marks on his back. A Justice of the Peace sentences Rambo to 35 days in jail. In the basement, the sight of wet, cramped cells triggers memories of captivity in Vietnam: a pit covered by a bamboo grate where he was starved and tortured. An extended flashback recounts his capture, forced labor, escape through the jungle while delirious with dysentery, and a trek of nearly 400 miles to American lines.
Back in the jail, Teasle orders Rambo's hair cut and face shaved. When a deputy named Galt brings a straight razor, the sight of the blade triggers a flashback to the enemy officer who sliced Rambo's chest during captivity. Rambo snaps, grabs the razor, and slashes Galt across the stomach, killing him. He charges upstairs through a door Galt forgot to lock and bursts outside with a stolen gun. He commandeers a motorcycle and races toward the mountains.
Teasle organizes a pursuit, enlisting Orval Kellerman, a 72-year-old retired tracker who was his late father's best friend and raised Teasle after his father's death. Orval brings his hounds. By nightfall, Teasle leads a small posse of deputies into the hills. Rambo finds a moonshiner's camp and negotiates food, clothes, and a rifle by leveraging the man's need to protect his illegal still.
The next morning, the posse picks up Rambo's trail while a helicopter with a police sharpshooter patrols overhead. Teasle struggles to keep up with Orval's pace but rediscovers the rhythm of running from his Marine boxing days. His wife, Anna, has left him, and the marriage is ending.
Rambo narrowly avoids the helicopter but is forced onto a bluff where he traps himself between cliffs on three sides. He descends a 200-foot rock face while the helicopter gunman fires at him. With no toeholds left, Rambo drops into a fir tree below, cracking ribs against a limb. He steadies his rifle and kills the gunman with a single shot. The pilot loses control, and the helicopter clips the cliff and explodes.
From the forest below, Rambo turns the pursuit into an ambush. He shoots five of the six dogs and then, as Orval bends to mercy-kill a wounded hound, shoots the old man in the back. Panicked return fire wastes most of the posse's ammunition. Teasle realizes he has not been chasing Rambo: Rambo has been leading them into a trap.
A thunderstorm transforms the bluff into a raging streambed. Teasle and deputies Shingleton and Ward try to carry the wounded Orval to safety, but floodwaters sweep Orval off the cliff. Several deputies desert in panic. Rambo hunts the posse through the storm. He kills the deserters at a cliff niche and slits the throat of Mitch, a loyal deputy. When Rambo fires at the fleeing Teasle, Shingleton grabs Rambo's rifle to throw off his aim; Rambo shoots Shingleton dead. Teasle flees into the darkness. Rambo pursues him for hours, but Teasle escapes into a vast bramble thicket.
Teasle crawls through the brambles all night and is found by a state trooper at dawn, barely alive. Rambo, feverish with cracked ribs, takes shelter in an abandoned mine shaft. From the entrance, he sees hundreds of lights along the roads: Teasle has mobilized a massive force.
From a communications truck, Teasle coordinates the search alongside Captain Kern of the state police despite severe injuries and a growing pill dependency. Colonel Sam Trautman, who directed the Special Forces school that trained Rambo, arrives by helicopter. Trautman admits deep ambivalence: He takes both pride and disappointment in his former student but acknowledges the killing spree was inexcusable. He reveals that Rambo's mother died of cancer, his father had an alcohol addiction and once attacked him with a knife, and Rambo enlisted expecting to be drafted. Trautman agrees to help.
At dawn, National Guard, state police, and officers from multiple cities sweep inward from all compass points. Rambo evades the sweep by running toward the advancing line and burying himself in mud beneath tree roots, letting searchers walk over him. After the line passes, he kills two soldiers. The gunshot alerts the searchers, but Rambo slips through a gap in the broken line and retreats to the mine, collapsing the entrance. He begins to surrender but feels a breeze deeper in the tunnel, suggesting another exit.
Rambo follows a harrowing underground route through branching fissures and into a chamber filled with bat guano and biting beetles. Near collapse, he forces himself back into the chamber. The bat colony flushes from the ceiling and swarms toward the exit. Rambo follows them and emerges from a basin in the hillside.
He steals a police cruiser and races into Madison, opening gas station pumps to flood the streets with gasoline and igniting chain explosions. Trautman pleads over the car radio for Rambo to surrender, but Rambo ignores him. He steals dynamite from a hardware store and detonates the courthouse and the police station, killing deputy Harris.
Teasle blocks the main road and confronts Rambo alone. He shoots out the cruiser's tires, sending it crashing. Rambo flees on foot through the burning town; Teasle pursues. Near a playground, Rambo fires and hits Teasle in the stomach. Teasle fires back and hits Rambo in the chest, shattering his already broken ribs. Both men go down.
Rambo crawls into a field of wild brambles and drags himself to the top of a small grassy mound. Numb from blood loss, he lies back and gazes at the flames reflected on the night clouds. He considers lighting dynamite to destroy his body but sees Trautman with a shotgun and Teasle stumbling behind. Rambo decides to die fighting. He aims his revolver at Teasle with nearly useless hands; the gun fires, striking Teasle. Trautman fires the shotgun, killing Rambo instantly.
Teasle lies in the field, no longer thinking of Anna or his ruined town. He feels an unexpected flood of something close to love for the young man who fought him so fiercely. He accepts death peacefully and dies.