A space shuttle crashes down to earth in a shower of debris two hundred miles wide. On that debris are some kind of spores that infiltrate the bloodstream and take away the emotions of their hosts, turning them into a single-minded hive consciousness intent on taking over the human race. Carol Bennel, a psychiatrist notices the changes and her doctor boyfriend identifies that the changes come about when the infected host goes to sleep. Unfortunately, she herself has been infected, but needs to remain free to save her son.

Jack Finney's classic scary story has had three official screen adaptations (INVASION OF THE BODYSNATCHERS in 1956 and 1978 and BODY SNATCHERS in 1993), one teen version (THE FACULTY in 1998) and a recent tv series INVASION. It's a popular story that lends itself to the concerns of the age. In the 50s it was the communist threat (or the homegrown McCarthyist menace), in the 70s it was the disconnection of the city dweller and in the 90s it was the dehumanising effect of military life.

It's a story that was an instant classic and one that it's almost impossible to mess up too badly.

And for the majority of its running time, THE INVASION doesn't mess it up either. Throughout the early sequences of mounting paranoia, people getting creepy, dogs going wild and society slowly falling apart, THE INVASION is every inch the spooky, creepy equal of its predecessors. By making the alien invaders act like a virus rather than a pod, the moments of mass infection are chilling, especially when the psychiatrist's own husband holds her down and deliberately infects her. This is a shocking moment that sets up the whole 'must not sleep' routine.

Unfortunately, about an hour before the end, someone realises that this is a quality scarefest and sets about grafting an action movie onto it for the sake of crashing some cars and stirring up some cheap thrills that are completely out of step with the rest of the film. It is ironic that a film about personality change should suffer such a change in personality itself.

It doesn't help that Nicole Kidman is no gun-toting mistress of disaster. She is not bad through the early phases, using the same mounting sense of panic and fear that she evoked in THE OTHERS, but is completely at sea with the final chase sequence.

She is ably, if unspectacularly, supported by Daniel Craig as the hero doctor, Jeremy Northam as the psychiatrist's husband and Veronica Cartwright (in a nice nod to the 1978 version) as one of her patients who might hold the key to saving everyone.

There are other issues apart from the whole car chase farrago. In the opening sequence, the head of the Center for Disease Control gets the lowdown on the infectious nature of the spores on the shuttle wreckage and then immediately takes hold of a piece of shuttle wreckage. You'd think that the head of the CDC might know better. The whole ease with which the heroes work out the solution to the problem with a quick look at the Carol's files beggars belief, as does the comedy russian routine that takes place at a dinner party halfway through.

If only the film had managed to have the courage of its convictions and stuck to the low-key scary stuff, it could have matched the classic '56 and '78 versions, but the crazy last half hour leaves it a diverting, but ultimately disappointing experience.

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