--- This is a retrospective review that reveals key plot points. If you haven't seen the series and don't want these moments spoiled, skip straight to the technical details and rent, borrow or buy the disk first ---

This week, a third series of the hit US TV thriller 24 starts on Sky One. Word is that the BBC let the franchise go after the first two seasons because "They wanted to give someone else a chance to screen it." How extraordinarily and uncharacteristically generous of them. It couldn't be, perhaps, that they could see that after just two series the formula was already becoming tired and that it was unlikely to pull in an audience big enough to justify the fee that they were doubtless being asked to pay for it?

A couple of weeks before the second series was due to start its much trumpeted first UK run on BBC2, Camus e-mailed me and asked "How can the 2nd series of 24 possibly be any good?" It was a perfectly reasonable question, because key to the narrative of the first series, as it is to any number of successful cinematic thrillers, is the concept of an identifiable character plucked from their normal life and placed in an extraordinary situation – as Jack Bauer says at the start of each episode, "This is the longest day of my life." So what would that make series 2 – the second longest day? An even longer longest day? It's inevitably hard to swallow that lightning could strike twice with such violence to the same person, hence the "Oh come on!" factor that dogs Die Hard 2 and any number of such sequels.

As someone who watched the first season of 24 every week on its original transmission and again on DVD, I have decidedly mixed feelings about it. Hailed both here and in the US as one of the most innovative slices of television in years, it was without doubt initially compelling viewing, an intricately plotted, expertly paced and sincerely performed thriller, driven along by edgy camerawork, sharp editing, fast action, and a driving music score. For my money, that's exactly why it has had such an impact. But much of the coverage focused on the programme's real-time structure, which was lost a bit in the UK, where the combination of PAL video speed-up and a lack of commercial breaks moved the action more into film time, something that has carried over onto the region 2 DVD release.

Confining the timescale of the series to twenty-four hours of real time does indeed have an impact on the story development, creating a tightly structured and sometimes genuinely exciting narrative, much of which stands up well to a second viewing, if only because it highlights the ingenuity of the scriptwriters and film-makers. The flipside of this is that elements that seemed weak on the first viewing are made to look all the more so a second time around. Kidnapping and threatening Jack's family members is overused as a plot device and comes across as lazy writing later on, and the whole amnesia plotline is not only hackneyed, but pretty much grinds part of the story to a halt until the condition is miraculously cured. Particularly disappointing is that the majority of the last episode kicks against the twists and turns of the preceding parts by being, for the most part, as predictable as hell.

Beyond the issue of pacing, the fact that the narrative unfolds in real time matters little. The clock that appears regularly on screen is not really there to tell the audience what time of day it is – advert break intros and outros aside, it appears to be about more how much longer this particular episode has to run. This actually works rather well when you are in the middle of action mayhem and the clock informs you that we are just six minutes from the end of the programme, winding you up over whether they will be able to resolve this situation before the credits roll. This use of the on-screen clock is not new in itself and was used to frankly better effect in Michael Crichton's fine 1972 TV movie Pursuit (which also dealt with a potential – but this time home-grown – terrorist threat), whose clock appeared on screen at irregular intervals, steadily counting down, but to what? It is very much part of the narrative structure of that film, especially in the final act, where Crichton uses this very clock to play a lovely trick on the audience and makes it a key element of the tension that follows.

Even less important to the structure here is the use of split screen, which in 24 is a purely transitional device to take us from one scene to another, having none of the narrative properties it had when used by Brian de Palma for a key sequence in Sisters, in which the police approach to a room in which a man has been brutally slain plays out alongside frantic efforts to cover it up before they arrive. None of this is necessarily a criticism – the on-screen clock and use of split screen may not be essential to the narrative, but the programme-makers have cannily made it utterly integral to the style of the series, so much so that if it were dropped from future series there would doubtless be howls of disapproval from fans.

Although the word 'innovative' is thrown around a lot in regard to 24, compared to fractured narrative of The Singing Detective, the surrealism of Twin Peaks, the revolutionary stylistics, editing and symbolism of The Prisoner, or reverse-narrative structure of films like Memento or Irreversible, it's fairly conventional stuff, just smartly done. The visual polish is accentuated by a cast for whom looking good seems to be as important as professionalism, with the only remotely ethnic-looking character, Jamey, later proving to be a traitor and thus not really part of the team at all. Kim Bauer manages to look sexy even when in mortal danger, and even Milo's computer-nerd scruffiness is studied and cool – these guys look less like counter-terrorist operatives than high-flying office workers (which, to a degree, they are). More than one female friend has admitted to me that a key attraction of the programme is that they think Kiefer Sutherland is hot. I doubt many tuned in to get sweaty over Ira Gaines or Victor Drazen.

Performances do help drive the narrative forward, but with a couple of exceptions the casting, in retrospect at least, feels dismayingly by the numbers. Pretty people are good, ugly, bearded or spectacled foreigners are bad, and there's one handsome, sexually potent terrorist on hand to serve as a warning to Anglo-Saxon women to stick to their own kind and not mess with these long-haired Mediterranean Romeo types. Kiefer Sutherland is probably the best cast of the lot, not on paper an obvious choice but an effective one, though over the course of this and the second series, his trait of delivering every line of dialogue in a sincere, urgent whisper has become a cliché in itself – the mere mention of the series' name prompts a good friend of mine to mimic Sutherland's delivery and say, "Just remember one thing – I love you!"

Though Jack Bauer occupies a traditional genre role of one man fighting against the odds, unlike key paranoia thrillers of the 70s, he is not an ordinary guy threatened by a covert government agency, but a key member of it. Taking a step back even from Mulder and Scully in The X Files, who as FBI operatives were fighting attempts to suppress the truth by their superiors, the members of the Counter-Terrorist Unit are presented very much as the good guys and protectors of the American way, a neat move by the programme-makers at a time when terrorist paranoia is still at an all-time high and the very word "terrorist" instantly labels a character as irredeemably bad. Of course, the terrorists here are foreign, and despite their posturing are not even dedicated to a cause – they're just in it for revenge and/or the money, ruthless capitalists in disguise, effectively eliminating the danger of anyone but Gordon Gecko empathising with their reasoning.

It's easy for a modern, gadget-hungry viewing audience to warm to CTU, whose offices are littered with all the (then) latest Apple computers, Titanium PowerBooks and Cinema Display monitors (and in case you think I'm prejudiced, this is being written on an Apple G4 iBook, which I'm perfectly happy with), whose cars contain portable fax machines and whose Palm Pilots can download live satellite surveillance pictures. Traditional family values are also key. Jack may have had his problems, but by God he'll to do anything – including threaten, beat and even kill – to protect his family (it is the failing of these values in the character of Sherry Palmer that proves to be her downfall). In this respect it seems less surprising that Nina should turn out to be a traitor – after all, she slept with Jack and possibly still has feelings for him, and as such violated the family unit at the narrative's centre and would remain a potential threat to it if not removed.

But perhaps the biggest surprise in the euphoria surrounding the first screening was that no-one seemed to have any problem with the presentation of modern America as an Orwellian society in which Big Brother is watching just about everything and everyone. Spy satellites are able to monitor seemingly every square foot of open ground, supposedly secure locks can be opened by punching the address up on a monitor at HQ, computer files and emails can be easily accessed and decrypted. Whatever you do, wherever you go, the government is watching, or at least has the ability to do so if it so wishes, and if it doesn't like what you're doing, then getting into your home, your business or your private files is a mere mouse click away. This is Homeland Security in action, and then some. The thing is, it's all presented here as a positive thing. Just a couple of years back, such a series would have shown us these very things to illustrate why Russia operated a closed and oppressive society in which its citizens had no real freedom. 24, and perhaps the audience's enthusiasm for it, suggests that the very definition of "freedom" needs to be re-examined in the context of modern America. To those opposed to George W. Bush and the liberty-curbing measures of his Patriot Act, this will not come as news, of course.

When it first appeared, 24 was something of a breath of fresh air, but even before the end of this first season it was showing the effects of the restrictive nature of its structure and narrative, and long before the end of season 2 the whole thing was looking a bit tired. Series 3 keeps pace with present paranoia by threatening "hundreds of thousands of innocent people" with a deadly virus, enabling the programme makers to continue presenting the loss of individual liberty and the freedom of covert agencies to do pretty much as they please in a positive light. With presidential assassination and nuclear and viral threats now ticked off the list of How To Make Sure The Audience Hates The Bad Guys, there aren't many places left to go. So here's a suggestion – try surprising us by taking an alternative look at the whole situation. Solve disputes through diplomacy rather than shooting everything in sight, have a look at just why people are angry enough to threaten such violence against a society, and have Jack realise that the technology he employs is as dangerous to liberty as it is helpful in fighting crime. Maybe they could even reflect on a few sobering truths about terrorism. One thing the 9/11 attacks should have taught us is that all the spy satellites and cruise missiles and palm pilots you can buy count for nothing when faced with a group of fanatically determined men armed only with knives and airplane tickets, and that sometimes, as with the Oklahoma bombing, the threat does not come from without, but within.

Nicely done menus with clips, graphics and sound-bites from the programme are easy to navigate, in part because there aren't actually that many options.

The transfer is 1.78:1 and anamorphically enhanced, and there is a degree of grain evident throughout, but otherwise the image is pleasing, with good colour rendition and excellent contrast, the black levels in particular being very solid. Widescreen is becoming the standard format for shooting TV drama in the UK, and even in the US the move to widescreen (for high definition broadcast) is taking over, but that doesn't always mean the DVDs will feature that print (Malcolm in the Middle, for example) and it's pleasing to see 24 presented in its correct aspect ratio. Shot on film as it is, this adds a cinematic quality to the look of the show.

As a TV show, it is hardly surprising that we have a Dolby 2.0 soundtrack rather than a 5.1 remix, but this still disappoints a little. Though centre-weighted, there is reasonable separation on sound effects and music, though this can be seriously enhanced if your amp has a decent DSP mode. Mine threw music in particular all around the room and really added to the audio experience of a show whose score is such a key part of its structure.

With no commentaries or documentaries, this disk set gets by mainly on the episodes themselves, but a couple of extras are included with the final episode on the last disk.

First up there is an Alternate Ending. This is anamorphic widescreen and the same quality as the main feature and accounts for 2 minutes 20 seconds at the end of the final episode, but offering a version that more fully meets audience expectations – that is, where Terri lives and everything is just dandy. That the film-makers did not go with this option is to their considerable credit.

And then there is the Preview Season 2 (1:30). You expect a trailer of the second series, but what you get is Kiefer Sutherland reading an autocue to camera and telling you what a fine, upstanding guy Jack Bauer was in series 1 and what a clever little series 24 is. This is utter bollocks, but still an interesting inclusion for completists.

24 season 1 still stands up well as a televisual thriller – it has style, pace and inventiveness to spare – but the formula grew old very quickly and this series will inevitably end up being cheapened by those that follow, as they cover the same ground repeatedly from only slightly differing angles. It remains both intriguing and worrying for its political subtext, which its more rabid fans seem determinedly blind to or simply not bothered by. It will be interesting to see how the series is viewed by future generations of political and media theorists – about what it says about American society of the time, the TV Network that commissioned it, and the fan base it attracted. Should we ever get to series 9, it would be a shame to forget, despite its weaknesses, how inventive, how well made, and how subtextually chilling this first series actually was.