RECALLING Margaret Thatcher's opinion that there is no such thing as society, the serial killer on the rampage in Tom Shankland's debut feature is driven by the disillusioned view that there is no love. If you can imagine Saw crossed with Sophie's Choice, you may begin to get the measure of this unsparingly violent police procedural thriller.

"There will be pain," declares the killer as yet another victim is subjected to a cruelly sadistic fate. As a detective (Stellan Skarsgård) investigates the case with his intuitive new partner (Melissa George) they note that what appears to be "WAZ" is carved on the tortured bodies of the victims. The central character in that word is delta, they find, and W-Delta-Z is an algebraic equation that supposedly proves there is no altruism in nature.

There is precious little of it in this grim, bleak movie set in a city that is hell on earth, a world of squalor, depravity, addiction and inhumanity. The film is set in the US but was shot in Belfast - so effectively that this information comes as a surprise in the closing credits - along with locations in Manhattan and Brooklyn.

Playing an archetypal hard- boiled, world-weary cop, Swedish actor Skarsgård appears to have modelled his accent on Clint Eastwood at his most gravel- voiced, but he is far more effective than the English actors playing Americans in the movie.

Having assaulted our senses with graphic gore in its early sequences, and having added the aural torture of some indistinct dialogue, WAZ steadily builds in atmosphere in the second half as it follows a twisting course to revelation and resolution.