|“||Well, you never know...you just never know. You just go along figuring some things don't change ever, like being able to drive on a public highway without someone trying to murder you. And then one stupid thing happens. Twenty, twenty-five minutes out of your whole life, and all the ropes that kept you hanging in there get cut loose, and it's like, there you are, right back in the jungle again. All right boy, it was a nightmare, but it's over now. It's all over.||„|
|~ David Mann|
He is portrayed by the late Dennis Weaver. Both the character and performance have been praised.
Mann is a middle-aged Los Angeles electronics salesman driving his red 1971 Plymouth Valiant sedan on a business trip. On a two-lane highway in the California desert, he encounters a grimy and rusty 1955 Peterbilt 281 tanker truck, traveling slower than the speed limit and expelling thick plumes of sooty diesel exhaust. Mann passes the unsightly truck, which promptly roars past him and then slows down again. Mann is unmoved, passing the truck a second time, and is startled when it suddenly issues a long air horn blast.
Mann arrives at a gas station, and the truck follows. While there, Mann phones his wife, who is upset with him for not confronting one of their friends at a recent party who was making a pass at her. Mann claims that he does not like confrontation and hangs up. The gas station attendant refills Mann's car and mentions that Mann needs a new radiator hose, but he refuses the repair.
Once both Mann and the trucker are back on the road, the truck begins blocking Mann’s path each time he attempts to pass it. At one point, the truck driver (Carey Loftin, whose face is never shown) waves Mann past, indicating it is safe to overtake. When Mann does, he almost strikes an oncoming vehicle. Mann realizes the truck driver was trying to trick him into a fatal collision. He passes the truck again, using an unpaved turnout next to the highway. The truck soon begins to tailgate Mann at high speeds—over 90 miles per hour—forcing him to maintain his speed to avoid being rear-ended. The chase continues down a mountain road with the truck bumping him several times until the Plymouth goes off the road, colliding with a guardrail across the road from a diner. The truck keeps going.
Mann enters the diner (Chuck's Café) to compose himself. After returning from the restroom, he is shocked to see the truck parked outside. Mann studies the diner patrons carefully and begins an inner monologue in which he contemplates the driver's motives and second-guesses his decision to sit helplessly in the diner. Most of the patrons sitting at the counter give Mann the impression of malice, but when one leaves, appearing to approach the tanker, he instead drives away in a pickup truck. Mann eyes the patrons again to try to identify his pursuer, and when he thinks he has, Mann confronts him. The man he approaches is angered by Mann's accusations and engages him in a short fist fight. After the café owner breaks up the fight, the falsely-accused man drives away in a livestock truck. The tanker truck leaves a few seconds later, suggesting that Mann's tormenter was never inside the diner in the first place.
Mann leaves the café and stops to help a stranded school bus, but his front bumper becomes caught underneath the rear of the bus. The truck appears at the end of a tunnel. Mann panics, manages to free the Plymouth, and flees, but then is puzzled to see the truck helping the bus get moving. At a railroad crossing, the truck quietly approaches Mann's car from behind and starts pushing the Valiant towards a passing freight train. The train passes by just in time; Mann crosses the tracks and pulls off the road. The truck passes him by and disappears. Mann eventually catches up to the truck as it has stopped, as though it were waiting for him.
Mann then stops at Sally's Snakerama Gas Station to call the police and refuel his Plymouth. The truck has stopped just a little further up the road. When Mann steps into a phone booth that is shielded from the truck driver's view, the truck roars up and plows into the telephone booth; Mann jumps clear just in time. The truck proceeds to chase Mann, who is on foot, destroying Sally's Snakerama and releasing several rattlesnakes that had been caged on the premises. Terrified, Mann jumps into his car and speeds away. Mann then hides behind an embankment off the road and sees the truck pass by, apparently without noticing him.
After a long wait, Mann heads off again but is dumbfounded to see that the truck is waiting for him just around the bend. Mann stops his car, then attempts to pass him, but the truck keeps blocking his way. He tries to approach him on foot, but the truck keeps driving away. He attempts to get help from an older couple in a car that is cruising by. They think he is crazy and refuse to listen, until they see the truck themselves; they flee when the truck backs up towards them at increasing speed. Mann returns to his car. The truck eventually allows him to pass by and a high-speed chase begins. Mann races up steep grades, putting some distance between himself and the truck. During the chase, he sees a black-and-white car (a 1971 Chevrolet Bel Air sedan) parked on the side of the road with writing on its doors. Thinking it is a police car, Mann skids to a stop next to the car only to realize the writing says "Grebleips Pest Control" ("Grebleips" is "Spielberg" spelled backwards). The truck follows him off the road and comes close to smashing the other car as Mann speeds off again. The chase continues up a mountain, but Mann's Valiant begins to overheat when its weak radiator hose fails. The truck quickly begins gaining on him. Mann barely makes the summit and coasts down the other side in neutral as the truck bears down on him.
Descending at speeds too great to control, the Plymouth spins out and hits a rock wall. The truck speeds toward the damaged car as Mann accelerates, drives up a dirt road, and turns to face his opponent on a large hill overlooking a canyon. Fed up and finally having overcome his distaste for confrontation, Mann engages the trucker in the titular "duel". He places his briefcase on the accelerator and steers his vehicle directly toward the oncoming truck, jumping from the car at the last moment. The tanker hits the car, which bursts into flames, partially obscuring the truck driver's view. Too late, the truck's driver realizes he is headed for the edge of a cliff and brakes hard. With a blast of the air horn, the truck plunges over the edge of the cliff into the canyon below, destroying the truck and car. A dark viscous liquid is shown dripping from the steering wheel. Above the smoking wreckage, Mann sits exhausted at the cliff's edge tossing stones into the abyss as the sun sets.