An aggressive cop movie, "Narc" grabs the audience by the scruff of the neck and threatens to throw 'em down the stairs.

The sense-assault begins with a frantic, handheld camera opening sequence. Undercover cop Nick Tellis (Jason Patric) chases down a drug-fuelled crazy, only to wind up suspended when the collar goes awry.

Months later he's offered a way back: to team with hard-ass lieutenant Henry Oak (Ray Liotta) and discover who offed Michael Calvess (Alan Van Sprang) - a fellow narc and Oak's best friend.

It's a redemption yarn, then - off-screen as well as on. Patric needs to atone for "Speed 2: Cruise Control", and Liotta's never lived up to the promise of "GoodFellas".

Both bury their histories with career-redefining performances.

Patric is still a detached, steely actor, but it's appropriate here, as his dedication to the job forces him to freeze out his family.

That he manages to hold his own opposite his domineering co-star is some achievement.

Liotta gives a fearsome, full-blooded, OTT performance that successfully stops a couple of slices short of ham. It's magnificent.

Nearly as bullying as Liotta's bulldozing presence is writer-director Joe Carnahan, who browbeats the story with style - using a blizzard of camera tricks to distract from the somewhat predictable narrative.

That it's relatively easy to unravel the investigation undermines some of Tellis' head-scratching scenes, but doesn't detract from moments of knuckle-gnawing tension as he stumbles toward the truth.

This is an old school, 70s-style cop thriller about old school, 70s-style cops - a 21st century "French Connection".

Carnahan's camera constantly suggests violence, while his barbed, believable dialogue and ambiguous, conflicted characters illuminate the moral quagmire coppers can sink into.

"It's got nothing to do with rules and regulations, it's got everything to do with right and wrong," bellows Oak.

You know he's right. You know he's wrong. You know this is a clever, thought-provoking thriller.