A young chap wakes up in a bare cell to find a spiked venus flytrap contraption bolted round his head and ready to snap shut unless he finds the key.

Which has been surgically lodged behind his eye. Scalpel, nurse?

Yes, we're back in Saw-land, a netherworld bled of all colour where the morally unsound meet their maker (or not) in a series of increasingly inventive ways.

This time round jaded detective Eric Mathews (Wahlberg) is called in to find the killer of the flytrap victim only to apprehend the ingenious Jigsaw with surprising ease.

However, there's a catch. While arresting the warped mass murderer in a derelict factory, Mathews discovers a bank of TV monitors displaying eight corpses-in-waiting imprisoned in a booby-trapped house.

That's bad enough... but the doomed group, who have just hours to live after gulping in lung-fulls of ricin gas, also include his estranged son Daniel.

Director Darren Lynn Bousmann appears happy with the "if it ain't broke don't fix it" philosophy and basically builds on the gruesome template of the original.

However, a bigger cast and a looser feel to their internment in a larger space inevitably relaxes the brooding tension which was such a plus first time round.

Where he does score highly are the ingenious plot twists (superior to the original) and a terrific final reel which wrong-foots viewers who've probably had their hands in front of their face for the last hour.

Tobin Bell reprises the role of Jigsaw with relish (he's the guy to hire if you can't afford Hollywood loon-in-chief Christopher Walken) and Wahlberg sleazes into the role of the dodgy cop.

It's slick, nasty and effective and who could dismiss a film that boasts the line: "You gotta think outside the box... or your son's going to end up in one."

Tim Evans