When the film's hero, Truman Burbank (Jim Carrey), talks to himself in the bathroom mirror before work each morning, his private musings and fantasies are being broadcast world-wide. A camera is hidden in the dial of his car radio, and there are several more positioned around his office.
All the people with whom Truman converses are actors, choreographed to guide or obstruct him, or simply to work in a bit of product placement. Even his home town of Seahaven is just a giant set. The night sky is muffled and starless because it's not a sky at all; it's a canopy.
On one level, The Truman Show works as an extended paranoid fantasy. Everything in Truman's existence is designed to prevent him discovering the central truth of his life, from the team of wheelchair-bound actors dispatched to delay his progress along a hospital corridor, to the teacher who rebuffs the young Truman's ambition to be an explorer by unfurling a map of the world and shrugging: "You're too late - there's nowhere left to discover."
But the film doesn't sanction the possibility that this could all be Truman's justification to himself for being a sad no-hoper who has never left his home town. Instead, Andrew Niccol's screenplay attributes blame to a largely malevolent God figure named Christof (Ed Harris), the programme creator who masterminds the whole project, down to the last camera angle.
There are some nice touches of ambiguity in Christof's character, such as when he caresses a giant television picture of Truman sleeping, and it strikes you that their relationship is not unlike that of Dr Frankenstein and his creature.
However, it's a serious failing of the film that the buck stops with Christof. In Groundhog Day, one of the finest American movies of the past 20 years, fate was a cruel and intangible presence with no discernible human incarnation - Bill Murray was tormented by having to live the same day over and over again without ever understanding why. And then, at some point, the cycle stopped. Yes, he had become a better person, but the film neither proposed solutions nor administered blame, and so the supposedly happy ending was stamped with lingering question marks.
Having an identifiable villain simplifies matters, but it also significantly undercuts our disorientation. The power of The Truman Show depends on how successfully it maintains the tension between the comical implausibility of Truman's imprisonment, and its sinister proximity to our own world. If it isn't nearly as unsettling as it should have been, that may be partly because in this country we have Noel's House Party, and nothing else can ever be truly terrifying once you've seen that.
The connection isn't a spurious one. That programme features a section in which a secret camera observes an unwitting viewer watching television at home, before the curtain is tugged back and the subject is made aware that his or her private life has been rendered public for the preceding few minutes - that their basic sense of reality has been fraudulent. It's the most terrifying thing on television - the tomfoolery of Candid Camera given an ugly, Orwellian twist.
The Truman Show uses this device to explore the breakdown in divisions between public and private life. When Truman is reunited with his father, whom he had long believed to be dead, the moment is real as far as he is concerned. What he can't hear is the dense orchestration that is being used by Christof ("Fade-in music") to garnish the reunion.
It's a clever moment, and one that is potentially incriminating for the movie - an insert that depicts calculated manipulation in a film that is itself frequently guilty of the same crime.
At many points during the picture, we are watching not only The Truman Show the film but The Truman Show the television programme; the film even begins with phoney opening credits.
It is not the first movie to establish an interior artificial reality, but, unlike This is Spinal Tap, it doesn't remain within the boundaries that it has established. A scene of the band members taking drugs was cut from This is Spinal Tap because it was argued that the group would never have allowed documentary film-makers to shoot compromising footage. Although the world depicted by the film was fictional, its own internal rules were never contravened.
How chilling the vision of The Truman Show would have been if the movie had stranded us exclusively within The Truman Show the television programme.
But each emotive cut from the general public hypnotised by their TV sets, back to Truman trying to escape from his artificial world, further diminishes the film's attack on Christof's manipulative tendencies. What is the juxtapositioning of two or more separate images to create an emotional effect, if it isn't manipulation?
The Truman Show most seriously exposes its own hypocrisy when Truman is making his getaway from Seahaven to be with the film's only other non- performer - Sylvia (Natascha McElhone), a woman from whom he was forcibly separated years earlier, but whose memory motivates his search for truth much like the mysterious female face in La Jetee.
Until this point, the picture has been characterised by an intriguing sterility that makes few claims on our emotions. This extends to Jim Carrey, who gives a marvellously understated performance that ping-pongs between timid and slightly seething, most notably during the excellent scene where he is trying to convince his wife that the apparently random behaviour in their neighbourhood is, in fact, a choreographed loop of action; he trembles with the hysterical conviction of a man who wants what he most fears to be true just so that he will know he isn't insane.
The director, Peter Weir, lends Seahaven the science-fiction coldness of Invasion of the Body Snatchers. As he proved in Picnic at Hanging Rock and The Last Wave, he is adept at this kind of enigmatic menace. But during the climactic scenes, he sacrifices this in order to whip up some good, old-fashioned tension, switching from cheering audiences of various nationalities to Truman "ripping through" the shell of Seahaven in an effect borrowed from Time Bandits.
A film that has demonstrated the futility in giving an audience exactly what it wants finally relents and gives the audience exactly what it wants.