It was not the death of a president. It was the death of the president. More 4's newspaper ads captured the moment: George W Bush emerging from the Sheraton Hotel in Chicago and falling forward, his hands clutched below his chest. It is an image of wish-fulfilment that already will have found its way on to the walls of many a student's digs. But be wary, warned this documentary drama, of getting what you wish for.

In the first place, you'd get Dick Cheney, whom the indefatigable Joan Didion recently described in the New York Review of Books as a character with a talent for turning life's lemons into lemonade, then spilling it and making others mop up the mess. History would be mopping up a Cheney presidency for decades. The next unintended consequence, argued Death of a President (9pm, 9 October; repeated 13 October), would be a tightening of the state's squeeze on civil liberties. Stand by, citizens of America, for Son of Patriot Act.

For all that, Gabriel Range's film was an exercise in wish-fulfilment - fulfilling, at least, the wishes of anyone hoping that Bush's unpopularity will swell into a toxic cloud of anti-neo-con sentiment. By 19 October next year, the film predicted/hoped, half of America would be on the streets, united in its hatred of the man - not just because of Iraq, but Iran, Afghanistan, the US economy and North Korea, too. (More 4 must have decided to show the film now rather than next month in case the midterms bring us a repeat of November 2004.) By dawn, the feds had 400 suspects in custody. One was Frank Molini, lead anti-Iraq protester. Another was Danny Williams, the "environmental nut". A third was Casey Claybon, a Gulf war veteran who had lost a son in Iraq. And then there was the al-Qaeda connection.

Cheney hopes against hope for it to be an al-Qaeda assassin. And Jamal Abu Zikri, an IT geek working in the building from where the bullet was fired, looks a good fit. Emotionless under questioning, he denies having ever carried a gun, despite his period of national service in Syria. Further spookery reveals he once visited a terrorist training camp in Pakistan. The case against him is clinched by forensic science. The only problem is that he didn't do it, and Claybon, who goes on to kill himself and leave a suicide note, did. Justice, natch, averts its gaze.

But what was this curious programme, with its retrospective, tell-don't-show documentary format, actually about? On one level, it was a metaphor for what had happened to America since 9/11. But 9/11 and its aftermath do not need a two-hour cinematic allegory. They have their own symbols: these are called the twin towers and Guantanamo. On another level, it was a simple "what if?" exercise and Range's gift as a writer was in empathising with the various POVs: the security guy felt personal guilt for letting the president down; the female speechwriter finally spoke of her crush; the FBI realised that its definition of the "right guy" differed from the government's.

But although the scenario was meant to be horrific and the treatment was superficially sober, one kept thinking how much fun it must have been to make. The cast members had been worked up in improvisation classes to replicate the way "eyewitnesses to history" speak on camera, and were as naturalistic as actors get. The CGI lab revelled in seamlessly inserting them into real footage, Zelig-style. A particular triumph was getting - in near-perfect lip-sync - Cheney to deliver Bush's funeral oration. In short, Range, who also directed The Day Britain Stopped, the 2003 pseudo-doc about transport snarl-ups, continues to make merry parodying the conventions of the documentaries of his earlier career. It was a good act, but at its tin heart, Death of a President was Time Trumpet without the jokes.

Andrew Billen is a staff writer for the Times

Pick of the week

Prime Suspect: the final act
15 October, 9pm, ITV1
Jane Tennison has hit the booze, and retirement age. Let's see if this ITV warhorse has still got legs.

Suez: a very British crisis
16 October, 9pm, BBC2
Fifty years after a canal ran through Mrs Eden's drawing room, she speaks. James Fox plays late hubby.

Man to Man with Dean Learner
20 October, 11pm, Channel 4
Chat-show spoof and sequel to a little-known comedy masterpiece.