"The Bourne Ultimatum" is the third and purportedly final entry in a series that has been very loosely based on the novels by Robert Ludlum. It's a tighter, more involving film than 2004's "The Bourne Supremacy," but still not quite at the level of 2002's more character-rich "The Bourne Identity." Though this latest picture does not add up to as much as the setup warrants, director Paul Greengrass (2006's "United 93") is an expert at shooting taut, adrenaline-fueled, and most importantly coherent action scenes. It's a specified talent that serves him well here: "The Bourne Ultimatum" is as close as one can get to making a nonstop, two-hour chase flick.

Amnesiac former assassin Jason Bourne (Matt Damon) is back, three years removed from the painful death of his girlfriend Marie and edging slowly but surely to uncovering who he once was and what led him to the torturous experiments his mind keeps flashing back to. When power-hungry CIA operations director Noah Vosen (David Strathairn) sends out the order to snuff out Bourne and anyone connected to him, Jason must elude those that want him dead as he presses forward with his own self-discovery mission. He's at least got a few people on his side this time: CIA investigator Pamela Landy (Joan Allen) doesn't like Noah's crooked work ethic one bit and attempts a plan of recourse, while agent Nicky Parsons (Julia Stiles) comes to his aid with a newfound empathy for what he is going through.

"The Bourne Ultimatum" was written by Tony Gilroy (2000's "Proof of Life"), Scott Z. Burns and George Nolfi (2006's "The Sentinel"), a study in storytelling economy where the screenplay's total dialogue could almost be jotted down on a bar napkin. Protagonist Jason Bourne is an especially light talker, but he doesn't have a lot of time for chit-chat anyway, what with the constant pressure of always literally being on the run. Matt Damon (2006's "The Departed") fits the persona of Jason Bourne every few years like a well-worn sweater; he's fantastic in the role, particularly when it comes to the physical demands, but said part's lack of growth does put a damper on how far Damon is capable of taking it.

The rest of the characters are used in an obligatory fashion. David Strathairn (2007's "Fracture") strikes one note as rotten-to-the-core CIA director Noah Vosen, himself a thinly disguised stand-in for several top politicians that will go unnamed. Joan Allen (2005's "The Upside of Anger") is memorable if underutilized as returnee Pamela Landy, now a growing ally of Bourne's despite having never come face-to-face with him. Also making an encore appearance is Julia Stiles (2006's "The Omen"), her role as Nicky Parsons beefed up significantly from the previous films. Stiles is a welcome face, but one senses the motives of her character were left on the cutting-room floor; there are a lot of suggestions early on that she has something crucial to tell Jason about his past—"You really don't remember, do you?" she says in one scene before they are interrupted—but this is abruptly dropped and no revelation ever comes. Because of this, Nicky's very participation is superfluous and it's more than a little confusing why she is suddenly putting her own life on the line to help him.

If "The Bourne Ultimatum" is left wanting in substance, the film makes up for it in pure energy. Relying on complicated stunt work over computer-generated effects, gritty handheld cinematography by Oliver Wood (2005's "Fantastic Four"), and masterful editing by Christopher Rouse (2006's "Eight Below"), the action and slow-burn tension pulses throughout and rarely lets up. The noteworthy set-pieces come fast—i.e. one set at the Waterloo train station in London, a high-octane car chase through the New York streets that gives the recent "Live Free or Die Hard" a run for its money—but the highlight is easily a silent, twenty-minute, three-way game of cat-and-mouse between Jason, Nicky and Agent Desh (Joey Ansah) through a Moroccan maze of buildings, alleyways, and rooftops. This segment all by itself is singularly brilliant in its fluid escalation of suspense and intrigue. The surrounding ninety minutes are good enough to satisfy action buffs and fans of the series—it really is well-mounted for its genre—but that sequence hints at how much better the picture might have been. As a franchise ender, "The Bourne Ultimatum" is solid but not overwhelming. If another sequel does happen to be made in the future, Jason could afford to be given a little more meat and complexity.