REVIEWED - UNKNOWN WHITE MALE: IT SEEMS fair to point out that there is what you might call a contextual spoiler in the second half of this review. If you don't know anything about Unknown White Male and you fancy the prospect of a documentary about an amnesiac becoming reacquainted with the world, then stop reading after this paragraph and get yourself to the cinema.

In 2002, a young English stockbroker named Doug Bruce woke up to find himself riding the New York subway towards Coney Island. All memory of his affluent life had been erased. When an old buddy, Rupert Murray, a film-maker, heard Doug's story, he rapidly realised that a man's attempts to rediscover his personal hinterland could form the basis for a fascinating documentary. And so it proved.

We see Doug, who looks eerily like a less brutish Liam Gallagher, enjoying chocolate mousse as if for the first time. He delights at the novelty of fireworks. His girlfriend describes him coming home one day with an extraordinary revelation: "I've discovered this great band - The Rolling Stones."

As the film progresses, it becomes hard not to marvel at the striking way the story takes on the quality of a gripping melodrama: a little bit Regarding Henry, a little bit Flowers for Algernon. How delightful that Doug, once a bit of a lad, seems to discover a sensitive side. Isn't it inspiring the way his photographic portraits become that bit more subtle after the memory loss? And everyone is just so darn good-looking in the picture. It's unbelievable.

Well, quite. Since the film's recent release in Britain, more than a few people have begun to question its authenticity. There is an odd irony here. If Unknown White Male is genuine, then it's no more than a decent, slightly worthy endeavour. If it is a hoax then - having played in major film festivals and lured the likes of Baroness Mary Warnock to appear - it is a genuinely fascinating and highly skilful experiment in deception. Either way, it works as a singular conversation piece.