The Saw franchise's blade is sharpened in the fourth outing for torture porn's box office juggernaut. Last Halloween the disappointing Saw III took $33.6 million in its opening weekend in the US, but the screenwriters made the heinous mistake of killing off the franchise's distinctive, sadistic villain (Tobin Bell). D'oh! Still, in horror movies death doesn't have to be final and Jigsaw returns - via flashbacks - as this convoluted sequel reveals his origins while putting the thumbscrews on another bunch of C-list actors (Scott Patterson from Gilmore Girls take a bow). Like the rest of the sequels the dank lensing, edgy editing and anatomically-correct parade of viscera give it a grim, nihilistic edge: think a snuff movie shot by the Marquis de Sade in a Soho toilet. Put that on the poster...