You may find reviews of 'Stargate: Continuum' inflated because of its contrast to the preceding 'Ark of Truth'. Whereas 'Ark' was in many ways, but not completely, a huge disappointment, 'Continuum' is and does everything 'Ark' failed at: the plot grips you, and isn't so linear; it surprises you, twists unexpectedly, rolls back on itself and weaves several arcs together, just like any good story should; there's genuine character development; and a deepened attention to detail and realism. Take your pick on one of the best ever 'Stargate SG-1' episodes, and imagine it being given the royal, feature-length treatment. 'Continuum' finally realises this notion without the symptoms of a clumsy transition between 42-minute episodes and an attempted epic that 'Ark' suffered from.

For any of you who are new to the Stargate franchise, I will provide a brief explanation - but thankfully 'Continuum' doesn't make 'Ark's mistake of being incomprehensible for someone who hasn't watched Stargate for 10 years. The Goa'uld are a snake-like race of aliens who implant themselves inside humans, thereby taking total control of their bodies. Some of these aliens have amassed huge power, controlling vast fleets of ships and armies of "Jaffa" warriors, by using various technologies to give the impression that they are gods. Known as the System Lords, they have been conquering the galaxy for millennia. Near the end of 'Stargate SG-1', the System Lords were all but defeated - except for the most cunning, Ba'al, who managed to clone himself in an attempt to render himself unstoppable. 'Continuum' picks up after our heroes, SG-1 - the primary five-strong team taking orders from the U.S. Government to counter such inter-galactic threats - believe they have the last Ba'al remaining.

But Ba'al is tricky as ever and, as ever, Cliff Simon plays him with a delicious mix of scheming genius, elaborate malice and exuberant vanity that has made Ba'al the villain we love to hate and hate to love. Indeed, Cliff Simon gives his singularly best performance of Ba'al to date, and is without a doubt the star of the show. In one dedicated, extended, excruciating sequence, Ba'al's character is really given a playground with the feature-length treatment he's always deserved: if you know Ba'al already you won't be able to stop grinning; if you don't you will fall hopelessly in love. This scene is rivalled only by a truly tense hostage sequence that rivals the best.

In 'Continuum', SG-1 probably faces the toughest trials it ever has, causing the usually gentle-mannered Daniel Jackson to exclaim in profanities twice throughout the film. Initially this shocked me, as care is usually taken to ensure Stargate productions can be watched by all ages - but actually this elevation of maturity really added some welcome grit to the story, and is matched by a handful of graphic, gory killings. This grittiness is enhanced by the aforementioned attention to realism that a full-length movie allows time for. In your typical Stargate episode, being stuck in an ice cavern isn't all too bad - you'll find your way out soon enough. In 'Continuum' this entails that there's no light, you can't light a fire, your fast, hard breaths billow visibly through the air, you're shivering uncontrollably and eventually you'll get frostbite with dire consequences.

At its heart, 'Continuum' is a time-travel story - a staple of science fiction and certainly of Stargate - but handled much better than usual. Whereas the 'SG-1' episode 'Moebius' thought it could hush the time paradoxes it generated aside, 'Continuum' faces them head-on. However, like the best sci-fi, it doesn't attempt to deliver you pseudo-scientific explanations, it just highlights the puzzles for your attention - they're interesting issues as questions alone. Of course, the time-travel itself is no real focus of the film, but more of a device to shake things up; in a sense, 'Continuum' is one, big, Stargate-themed "What if?" Characters are tested to extremes, are forced to interact with completely different roles, and the opportunity is seized to throw in more guest appearances of old characters than you can count.

Besides all this praise there are some things 'Continuum' really lets itself down with. Some very awkward dialogue between the SG-1 members at the beginning reeked of the writer not really knowing what else to say - although there is an extremely bold speech from Vala, impressive only on account of the boldness of writing it in. Some crucial plot moments are swept over far too quickly - how quickly do you think you could be persuaded that your mortal enemy is actually your friend if you'd never met him before? Well, pretty damn quickly, 'Continuum' seems to think - although again there is enough material for the hardcore fan to "explain away" this kind of problem. It was also disappointing that Joel Goldsmith's score was disappointing - many scenes that really needed a strong sense of drama are overplayed by bright, bouncy music, which slightly jars; one thinks, "Aren't people dying here?" That said, it equally has its moments of grandeur.

'Continuum' succeeds by walking the line between returning to SG-1's roots and mixing up the formula. Original series developer Brad Wright writes, with direction from more recent talent Martin Wood. His flair really shows - watch out for an extended tracking shot in the first few minutes of the film that climaxes with the entrance of the heroes. Whereas 'Ark' doesn't at any point seem to know quite what it's doing, 'Continuum' feels guided by more confident creatives, resulting in a satisfying movie for fans of the show.