The main weapon in this grainy black and white take on that modern boogie man, the serial killer, is a very black humour. Just about the first thing we see is a riverbank lecture on the correct body weight to ballast ratios for the disposal of corpses (pay attention - there'll be questions later).

Set in the provincial Belgian town of Namur, a documentary film crew trails Ben, the arrogant, mouthy, rather ridiculous serial killer as he goes about his everyday business in pursuit of a decent living wage; each month he likes to open the scoring by popping off a postman to get his hands on the pension cheques in his sack. As we tag along for the ride we see men, women, old people, and children mercilessly throttled, shot, suffocated, and even scared to death - to save bullets - no one, if it serves his purpose, is spared Ben's ire. He will coerce and break his way into your home, or simply hijack a taxi and embark on a drive-by, all the time keeping up a lucid but entirely absurd, ill-informed dialogue on art, architecture, and the meaning of life.

This debut feature, shot on a shoestring over several years, was intended as essentially a show reel before netting a handful of major festival awards, and the reasons are obvious, for in making a joke of death - and in particular, violent death - the makers are asking their audience to question their very reaction to what's shown on the screen, what they are laughing at. And it is explicit in its depiction of the grotesque - opening with an innocent woman garrotted in a train carriage before proceeding with that lesson in body disposal; immediately rendering hysterical the initially traumatic.

What its makers are doing in essence is posing a serious question about the complicity of the media in the act of violence itself. How far are the film crew following Ben observing and how far are they implicated in his actions, and by extension, how far are the audience co-conspirators in their watching - laughing - as a man's head is repeatedly battered on his bathroom sink, or a pillow is held across a child's face on his own bed after witnessing the sadistic butchery of his parents?

The answer is more difficult to ascertain than one might suspect, with Ben, for all his idiocy, being a rather entertaining, beguiling kind of host. But here the three film-makers rather overstep the mark with their own absurdist touches, as if not entirely sure of the humour inherent in the central premise. Thus, we cannot help but question the notion that such a man could go about his work being filmed along the way without drawing attention, or the absurd Spinal Tap-inspired loss of sound-men in crossfire. The net result is that when the crew do become explicitly involved in holding the kid still, or taking an active part in the vicious rape and murder of a man and woman in their kitchen, their purpose is too masked, and thus too blunted, to be entirely successful. And the film outstays its welcome by a good quarter hour, dragging to a nicely turned but too obvious finale.

What is undeniable is that these former film students have crafted a very professional piece of work here, making inventive use of the form and conventions of documentary. particularly in the design of sound. Co-director and writer Poelvoorde plays Ben with a building sense of psychopathy that after a while is authentically scary in its casual switch from introducing us with obvious pride to his exceedingly bland family, to calmly studying film of a failed attack to see where he went wrong and the intended victim lived. As a portrait of a serial killer it is a fresh, provocative meditation on cinematic violence that should at least be seen before it's condemned, but at the same time is too easily dismissed for its broad, albeit sick, humour, lacking the sheer appalling blank nihilism of John McNaughton's Henry: Portrait of a Serial Killer, still far and away the best of the form to date.