Steven Spielberg's Duel needs remarkably little to turn an ordinary drive into a nightmare. David Mann travels through an isolated landscape, encounters a tanker truck and finds himself being relentlessly terrorized by whoever is behind the wheel.
We never properly meet that person.
This isn't missing characterization. It's one of the film's smartest decisions.
What attracted Spielberg to Richard Matheson's material was precisely the idea that the driver remained essentially unseen. By hiding the human being, Duel avoids answering the question most thrillers eventually feel obliged to answer:
Why is this happening?
A motive would make the situation easier
David Mann hasn't done anything significant to the driver. They don't share a history, and Mann hasn't accidentally stumbled into some larger criminal plot.
He's simply on the same road.
That randomness is what makes the situation so disturbing. A conventional villain usually has a motive, and motives create rules.
Revenge can be understood. Money can be negotiated. Even movie psychopaths are frequently given elaborate explanations so the audience knows exactly which childhood incident eventually produced the third-act confrontation.
Duel offers no such comfort.
Mann can't negotiate because he doesn't know what the other man wants. There may not be a rational explanation.
And if there isn't one, there may not be a rational way to stop him either.
The truck becomes the character
Because the driver remains hidden, Spielberg gradually transfers personality to the vehicle itself.
The truck isn't photographed neutrally. Its front has an aggressive, almost facial quality. Its engine becomes a voice, black exhaust surrounds it, and its enormous scale changes depending on how close it gets to Mann's much smaller car.
The collection of license plates adds another layer. Spielberg imagined them almost like trophies from previous victims. Whether we're meant to construct a literal history from them isn't particularly important.
The truck feels as if it already had a life before David Mann appeared.
The person driving it becomes almost irrelevant.
It no longer feels like a man in a truck is pursuing Mann.
The truck is pursuing him.
Mann is readable. His opponent isn't.
The imbalance is built into the film.
We see Mann's face, hear his thoughts and watch irritation turn into confusion and then genuine fear. He is emotionally transparent to the audience and physically visible to his pursuer.
He receives almost nothing in return.
A hand. Boots. Small physical fragments.
No face, no expression and no clear emotional response.
Mann can't tell whether the driver is furious, amused, calm or completely detached. He has none of the tiny signals people normally use to judge another person's intentions.
His opponent is effectively a blank wall moving at highway speed.
The rear-view mirror becomes a horror device
This decision also gives Spielberg one of his most effective visual tools.
The truck can disappear and return repeatedly: in a mirror, around a bend, on the horizon or among other vehicles.
Eventually the audience starts searching for it automatically.
If we knew the driver's face, some of our attention would shift toward reading the person behind the glass. Instead, the truck itself becomes the only information we need.
After a while, Spielberg barely has to show anything.
A small dark shape in the distance is enough.
Any explanation would make Duel smaller
It's easy to imagine a version that eventually reveals the driver and gives him a history.
Maybe he's unstable. Maybe Mann unknowingly insulted him. Maybe he has some elaborate reason for targeting strangers on the highway.
None of those answers would improve the movie.
The moment Duel explained the driver, it would place boundaries around him.
The unseen man has no boundaries because Mann has no information.
Spielberg never needed to show the monster behind the wheel.
By that point, the truck already had a face.