Starring Matt Damon, Brian Cox, and Franka Potente. Rated PG.

As spy movies go, The Bourne Supremacy has all the impact of a well-aimed right to the jaw. Loosely based on the Robert Ludlum novel, this is the frenetic sequel to The Bourne Identity. As such, it contains many of the elements that made the first movie such an adrenaline rush, not the least of which is another lean and hungry turn by Matt Damon as the confused Jason Bourne, a former CIA assassin who's still trying to piece together his old life through a slowly lifting fog of amnesia.

Revealing too many plot points in a movie like this would spoil a lot of the fun. Let's just say that Jason's attempt at a fresh start with the help of his understanding girlfriend (Franka Potente) comes to an early halt. After that, a lone Jason takes the offensive against his spooky old cronies in a story that's all about trying to find answers the hard way. Tony Gilroy's provocatively cryptic screenplay takes us down any number of blind alleys from Berlin to Moscow. Trying to make sense of it all will only give you a headache. The best thing to do is simply surrender to the frantic direction of Paul Greengrass, whose use of quick cuts makes the average James Bond movie look like the sleigh ride in Doctor Zhivago.

There's a lot to admire here in a transparent, summer-blockbuster kind of way. At the top of the list is the kind of toughness that you rarely see in movies anymore. There's a brutally authentic fight scene about a third of the way through, and a climatic car chase, with Matt Damon at the wheel of an increasingly battered Russian cab, is right up there with anything you've seen in classics like Bullitt or The French Connection.

Not that the performances take a back seat to the action. Joan Allen and Brian Cox hit all the right notes as a couple of uptight, world-weary CIA drones. But it's Damon who really delivers here. Stripped of his Bagger Vance baby fat, he has the sleek moves of a first-rate spy down pat. As an actor, Damon is only slightly better than his wooden pal Ben Affleck, but here his dialogue is wisely kept to a minimum. And the one emotion he's asked to display consistently--a kind of coiled panic that can spring into sudden bursts of violence--is well within his limited range. Another sequel is, apparently, in the works. As long as they're this good, I say keep them coming.