Blood up to the stump

“Saw”Lion’s Gate FilmsDirected by James WanWritten by Leigh WhannellStarring Cary Elwes, Leigh Whannell, Danny Glover and Monica PotterRated R/105 minutesOpens today

Four out of five stars

Despite an uncanny likeness to David Fincher’s opus, “Seven,” newcomer director James Wan’s incisively moralistic thriller “Saw” bristles with inventive horror gristle.

Deep in a putrid subterranean latrine, Adam (played by Leigh Whannell, who also wrote and produced the film) awakens shackled to a corroded pipe. On the opposite side of the room slumps Dr. Lawrence Gordon (played by Cary Elwes, fresh from Jim Carrey’s “how to overact with class” camp). Between the disoriented men lies a blood-soaked carcass holding a pistol in his hand.

A cryptic, distorted micro-cassette provides the captives with veiled clues and a few rudimentary tools-two hacksaws too brittle to cut through their fetters, but sharp enough to sever flesh and bone. The recording ultimately orders Dr. Gordon to kill Adam. If he fails to do so, he, his family and Adam (who hasn’t a prayer in either scenario) will be slaughtered.

Much like its harbinger, “Seven,” “Saw” preaches a twisted didactic message through the metered rants of a righteous madman.

This fellow, a slightly unhinged serial killer known as Jigsaw, fancies himself a demogogue. He thrusts morally errant individuals into morbid survival games in which they must demonstrate an all-encompassing zest for life, or suffer a horrific death. This often proves that one who values his life requires the killing of another, or inflicting great personal harm.

Jigsaw’s macabre puzzles, regardless of brutality, always fit the reprobate’s offense in some warped way.

For example, a man who slit his wrists awakens in a cage lined with a labyrinth of razor-wire. If he truly wants to die, he may pout in the corner and starve to death. If he clings to his lifeblood, however, he must be willing to spill it over and over again as he scrambles to find a path through the wire.

Impelling the plot saw tooth by saw tooth, Wan (aided by the nimble hands of cinematographer David A. Armstrong and editor Kevin Greutert) weaves seamless transitions into frenetic cut scenes and expository flashbacks, cinching an already taut net of terror like the webbing of a visceral tennis racket.

With that in mind, you can see how “Saw” could have very easily lost itself in a blood-spattered quagmire of morality. But thanks to screenwriter/producer/actor Leigh Whannell’s clever script, “Saw” consistently frays our nerves.

In short, “Saw” works-and it’s scary as hell.

Unfortunately, the tension wavers periodically, due to overwrought acting and poor handling of actors.

Danny Glover gives a lackluster performance as the grizzled Detective Tapp. Perhaps Wan just didn’t know how to make use of Glover, but his grumbling, obsessed investigator appears humorously disgruntled.

Cary Elwes as Dr. Gordon exudes British stiffness. This is strange considering that Elwes (yes, “The Princess Bride” Cary Elwes) is poised like a shaken can, inopportunely exploding with emotion. Wan really should have kept a leash on him.

Leigh Whannell is a godsend. As the sleazy photographer Adam, Whannell provides a much-needed terror reprieve. His knack for off-color comic relief seems to temper Elwes’ absurd outbursts, and helps the cast to maintain some semblance of cohesion.

Squeezed into a bursting little blood-packet, “Saw” delivers the most chilling, twisted thriller since “Seven.” If you have a penchant for ensanguined psychological fare, cinch up your tourniquet, take a deep breath and delve into Jigsaw’s realm.

[email protected]