Two confused strangers wake up shackled to exposed pipes in a dark and dingy bathroom with another man holding the gun he’s used to kill himself in one hand and a tape recording in the other.

It’s not a sick joke you’ve heard before, just the way Saw nicely starts out as not-too-much like any other shocking serial killer thriller you’ve seen before.

The bleakness of Se7en has seemingly become this genre’s decrepit scripture. And Saw earns points for at least finding a pulpy, compelling variation on that movie’s idea.

Much like that film’s John Doe, this film’s Jigsaw killer targets the dregs of society and those with sinful secrets. But nearly all of Saw is told from the victims’ perspective, making it a sadistic little corker in the early goings. 

As gory a guilty pleasure as Saw is at the outset, it falls prey to the postulate that no one knows how to end a thriller without resorting to surprise without sense.

A narrative blind side hit, Saw‘s final gotcha gets ya even if the film tips its hat to a grander villain at work. But thinking about it for 10 seconds ruins the thrill. (Who can hold their breath that long or find that perfectly timed a sedative?)

Saw gets bad before that, and aggressively so, resorting to the other thriller traps of cliches and overacting. Hasn’t Monica Potter’s character learned that the time for intimate confessionals about marital problems is not when you’ve got a murderous nut-job at gunpoint?

Wouldn’t Cary Elwes’ good doctor consider the possible problems of parking in a garage with all the lighting of a subway tunnel? This is before Elwes, as one of the two aforementioned strangers, confuses a psychological meltdown for wailing in the gruesome final moments.

He at least has some believable moments earlier, as his Dr. Lawrence Gordon fights against confusion and time to figure out just why he’s ended up captive in a room with young, outspoken Adam (Leigh Whannell, also the screenwriter).

Gordon learns that if he doesn’t kill Adam by a certain time, his wife (Potter) and daughter will be killed. Formerly suspected asthe Jigsaw killer, Gordon puts together that this is the work ofthe Jigsaw killer — a man infamous for placing people in physically or morally complex traps in which the victims sometimes have to kill or be killed.

But Gordon doesn’t know of the mental games that Jigsaw’s playing with Adam, a traumatized rogue cop on the case (Danny Glover) and pretty much every other character in the film.

There’s plenty of fine suspense and red-herring trickery sprinkled throughout the first hour. And director James Wan delves into the disturbing schemes of Jigsaw’s brutally intricate traps without turning us off to where the film is going. The flashback scene to Glover’s near-death (and apprehension) experience with Jigsaw is the best example of both.

The conclusion whips up a fair amount of dread that the bad guy’s going to win. But instead of generating armrest-gripping tension, the big reveal draws laughter. Like too many thrillers these days, Saw ends up being a sick joke on us.