It feels odd, during a week in which the film world lost two of its towering artists, to pick up the baton of reviewing summer blockbusters again. But The Bourne Ultimatum is an ideal place to re-enter the flow, because the pure jolt of narrative pleasure it provides reminds you just how powerful the pull of mainstream cinema can be. Paul Greengrass, who also directed The Bourne Supremacy and last year's nerve-racking United 93, is fluent in the idiom of the hand-held camera—an annoyingly overused technique but one that, at its best, excels at capturing disorientation, anxiety, and fear. Since these states of mind are the stuff of daily existence for the amnesiac spy Jason Bourne (Matt Damon), Greengrass is perfectly at home in Bourne's jittery world. I found United 93 almost too skillful for its own good, surer of how to wring a cold sweat from its audience than of what it wanted to say. But when the source material is a Robert Ludlum spy thriller rather than one of the worst days in our country's history, that level of directorial calculation is more than welcome.

Jason Bourne is a pretty calculating guy himself; since the death of his girlfriend, Marie (Franka Potente), in the second chapter of the trilogy, The Bourne Supremacy, he's been pursuing her killers around the globe under various assumed identities. At the beginning of Ultimatum, with Marie's death avenged, we find him more introspective and brooding than ever. Fragments of his past as a CIA-bred killing machine are coming back (often in the form of clips from the first two Bourne movies). En route to uncovering his pre-brainwashing identity, he's figuring out that the black-ops training program that stole his memory has mutated into something even scarier.

Under the direction of Noah Vosen (a silken David Strathairn), the agency has gone gonzo, surveilling and targeting journalists, passersby, even its own agents when they start asking too many questions about the top-secret Blackbriar project. Bourne does have two allies within the agency: Pamela Landy (Joan Allen), who's disillusioned by the dictatorial turn the agency has taken, and Nicky Parsons (Julia Stiles), a young agent who's been following Bourne since his pre-amnesia days. Nicky is the closest thing the movie has to a romantic interest, but Bourne, ever since losing his beloved to an assassin's bullet, has been a tough nut to crack. The fact that this action hero is still actively mourning his girlfriend two movies later is evidence enough that this is no typical franchise. Somber and melancholy, Jason Bourne is the anti-James Bond. He may not be able to remember his own name, but he can't forget Marie (and given that she was played by Franka Potente, possibly the coolest moll in the history of spy thrillers, who can blame him?). As for Stiles, though she's finally given something to do this time around, her blank, stolid manner is too much like Damon's to serve as a credible foil. The fiery Marie was someone you'd want to be chased through southern India with; Nicky just seems like a pill.

Still, allowing for a few action-movie commonplaces (the wincing hero bandaging his own wounds in a fluorescent-lit public bathroom; the CIA op grimly informing his superior that "we have a situation"), The Bourne Ultimatum feels fresher, leaner, and faster than any action movie in years. It zips from one acutely well-choreographed chase sequence to the next, most notably a high-tech manhunt in London's Waterloo Station and a one-on-one fistfight in an apartment in Tangiers. In this bravura sequence, scored only with the sounds of heaving breath and cracking bones, Bourne defends himself with whatever domestic weapon comes to hand: a book, a rag, a toothbrush. When he finally does his opponent in, a slack-jawed reaction shot of Julia Stiles stands in for the audience's own disbelief.

Whether this third chapter in the series will turn out to be The Bourne Penultimatum or even the Bourne Antepenultimatum is left in suspense by the ending. On the one hand, the ambivalent final frames all but bellow, "Sequel!" Then again, assuming Jason Bourne really did manage both to find out his true identity and to live to tell about it, what would be left for him to do?