not so much to suggest a sequel as to hammer home everything at stake. -Paul Tonks.

Fans of the original won't be disappointed, as there are more than enough shock moments in the first few hours to hint at the climactic build-up to come, while newcomers can quickly get involved in the lives of Jack and his family. There are some new characters to bolster the veteran cast and, interestingly (although not surprisingly given the outcome of the first series), Jack's character has taken an altogether darker, more psychopathic turn. The danger the characters find themselves in also has a much more global impetus, grounded as it is in the war against terrorism. Although the territory is more familiar this time around, this second series is just as much a high-tension, taut, adrenaline-fuelled ride as the first series, and one that will have you glued to your TV for the next 24 hours. -Kristen Bowditch Series 3: There's not one cougar to be found in 24's dynamic third season, and that's good news for everyone. After Jack Bauer's daughter Kim (Elisha Cuthbert) survived hokey hazards in season 2, she's now a full-time staffer at CTU, the L. A. -based intelligence beehive that's abuzz once again-three years after the events of "Day Two"-when a vengeful terrorist threatens to release a lethal virus that could wipe out much of the country's population. The intricately woven subplots that are 24's greatest strength are masterfully developed here, and character arcs are equally strong, especially among CTU staffers Tony (Carlos Bernard) and his wife Michelle (Reiko Aylesworth); CTU director Ryan Chappelle (Paul Schulze), who is season 2's tragic bargaining chip; and the annoying but well-intentioned Chloe O'Brian (Mary Lynn Rajskub), who makes pivotal contributions with by-the-book efficiency. It's 24's superior casting that overcomes the series' occasional lapses in credibility, and season 3's twists make marathon viewing a nerve-wracking delight. By the time it's all over, with a high body count and the surgical reattachment of a main character's severed hand, 24 once again leaves you gratefully exhausted. As always, Sutherland anchors the series in the role he was born to play. When Jack takes a private moment to release 24 hours' worth of near-fatal tension and psychological anguish, Sutherland proves that 24's dramatic priorities are as important as its thriller momentum. -Jeff Shannon Series 4: Hard to believe, but after all these years, 24 is as vital and compulsive as it always was. Fortunately, Jack's knack of attracting trouble hasn't deserted him either, and quickly, it's business as usual. Starting the series with a fresh romance, a different job and one heck of an explosion, it doesn't take long before Jack is back in action, and he's soon joined by a mixture of new and familiar faces. To talk about the plot would be unfair, as 24 is consistently a dish best served cold. Suffice to say that there's a heady mix of plotlines, twists and downright brilliant cliffhangers. Perhaps the cocktail isn't as fresh as it once was, and there are moments where you can't help but feel that plausibility is being stretched a little too far. But accepting that is part and parcel of the 24 experience, and arguably part of the fun. That's because even as it approaches its final stages, 24: Series 4 maintains a tremendous momentum and level of intrigue, and by the time the clock ticks for the last time at the end of the 24th episode, odds are you'll be thirsting for more. Bluntly, in spite of its flaws, 24 remains one of the most essential shows currently on television-and this series offers ample evidence why. -Simon Brew Series 5: The adventures of Counter Terrorism Unit agent Jack Bauer have rarely been dull. Yet after four series of battling the bad guys in real time, some could rightfully wonder whether 24 had lots its edge, and its ability to surprise. The fifth season should put any such doubts to shame. Set eighteen months after the dramatic finale to Season Four, things get off to a shocking and pulsating beginning. You won't find plot spoilers in this review, yet it's as if the writers realised they had some serious carpet-pulling to do to keep the show's audience intrigued once again. Set, as usual, over the course of one single day, there's then a slight lull in the first third, before things spring ferociously into life. Make no mistake: if you can overcome the usual need to suspend elements of your disbelief, this is the best series of 24 since the first, and as it winds near to its equally dramatic conclusions, it's simply hard to take your eyes off it. Joining the usual cast too is a procession of familiar names. Peter Weller (Roboocop), Sean Astin (The Lord Of The Rings) and C Thomas Howell (The Hitcher) are among those doing their curriculum vitae no harm, but the acting honours are taken by the wonderful combination of President Logan and his first lady, played by Gregory Itzin and Jean Smart. With a denouement that sets up a sparkling sixth season, this fifth series of 24 is a genuinely significant achievement. It's packed full of surprises, isn't afraid to take a few risks, and as all good thrillers should, it keeps you on the edge of your seat for far longer than is comfortable. A superb show, very much on top form. -Simon Brew Series 6: The further adventures of Los Angeles' Counter Terrorism Unit's finest initially sees Kiefer Sutherland's Jack Bauer in a Chinese prison and not in good shape. But, this being 24, it's not too long before the breakneck plot has revved into gear, and the wheels are turning again on a frantic real-time ride that's thoroughly in the tradition of what's become television's finest thriller. You won't be finding plot spoilers here, because half the fun of 24 is not knowing what unexpected twist the scriptwriters have for you around the next corner. All that matters is that the world is under threat, and it's up to Jack Bauer to lead the fightback. And it's Kiefer Sutherland that's the real asset to series six; whereas particularly in season five he took a sideways step to accommodate stronger supporting characters, here he's shouldering a greater degree of the show's narrative thrust. You'd be hard pushed to declare that season six is vintage 24, but that's more to do with the context of particularly the excellent run that preceded it. But few shows can match its audacious verve, and repeated ability to surprise and enthral. So while season six may have too many villains, and may ask you to bear with it through a few troughs, there's still nothing out there to match it. Jump aboard… -Jon Foster.

Picture and Dolby Digital sound are impeccable. -Mark Walker.