“The Bourne Ultimatum”

Those are words to live — or die — by. Especially if your name is Bourne, Jason Bourne.

In a summer of underwhelming threequels, "The Bourne Ultimatum" more than lives up to the lofty expectations triggered by memories of 2002’s "The Bourne Identity" and 2004’s "The Bourne Supremacy."

Echoing its exemplary predecessors, this third "Bourne" adventure positively overflows with bone-rattling, pulse-pounding chases, fights and hair’s-breadth brushes with death.

Unlike far too many big-screen thrillers, however, you don’t have to shift your brain to "neutral" to appreciate "The Bourne Ultimatum." Indeed, anyone who doesn’t pay close attention to the movie’s multiple machinations does so at his or her peril.

Not that it’s likely to happen, given the express-train pacing and gripping, relentless quest of a killing machine desperate to prove that he can — and must — go home again. If there’s any hope of recovering his humanity, that is.

Those unfamiliar with Jason Bourne’s shadowy world will need a quick primer to get up to speed.

In "The Bourne Identity," which retooled the late Robert Ludlum’s literary creation for a post-Cold War world, the amnesiac title character (Matt Damon) discovers he’s the MVP of a secret all-star CIA kill squad — and wanted (dead, not alive) by his former employers. In "The Bourne Supremacy," he must resume his covert ways when he becomes the leading suspect in a CIA hit connected to a black-ops program known as Treadstone.

In "The Bourne Ultimatum," Treadstone is no more.

But its replacement is even worse. Dubbed Blackbriar and under the control of upright, uptight Noah Vosen (David Strathairn), it’s a shoot-first, ask-questions-never outfit operating without government oversight.

That is, until the CIA’s director (Scott Glenn) assigns someone with previous Bourne experience to Blackbriar: no- nonsense agent Pamela Landy (Joan Allen), who may be able to help track Bourne, despite his record of outsmarting every assassin the CIA sends to take him out.

This time, it’s a baby-faced killer named Paz ("Domino’s" Edgar Ramirez), who picks up Bourne’s trail in London — where Bourne confronts a journalist who’s been writing some very incendiary articles about him. (Drat those pesky reporters …)

After which "The Bourne Ultimatum" globe-trots in high gear, taking our under-the-gun hero from Turin to Paris to Moscow (Berlin doubles for the Russian capital) to Madrid — where Bourne conveniently re-encounters conflicted, knows-too-much CIA agent Nicky Parsons (Julia Stiles).

Together, they travel to exotic Tangier, where Bourne and Parsons elude another CIA killer (Joey Ansah) — but not before a twisty chase through the teeming streets of the city’s old, walled Medina that leads pursuer and pursued over rooftops, through windows and into private residences, culminating in a desperate, hand-to-hand grapple for survival.

By then, Bourne has enough information to find his way back to New York, his "birthplace" as a CIA killing machine — and to the mind-control master (a quietly monstrous Albert Finney) who made him that way.

Unlike the first two chapters in the Bourne saga, "Ultimatum" focuses on answers, not questions, heightening the excitement as the title character comes ever closer to finding the object of his epic quest: himself.

Returning screenwriter Tony Gilroy (this time collaborating with "An Inconvenient Truth" producer Scott Z. Burns and "Ocean’s Twelve" writer George Nolfi) once again finds a way to bring Ludlum’s Cold War spy games into the war-on-terror present.

Of course, it helps that some of the author’s prevailing themes — particularly the ones centering on rampant conspiracies and out-of-control government programs — remain utterly, eerily relevant.

It also helps that director Paul Greengrass ("United 93"), back for his second "Bourne" go-round, has such a flair for you-are-there immediacy.

With his urgent hand-held camera style and blink-of-an-eye editing, Greengrass plunges audiences into Bourne’s edge-of-elimination existence — and keeps us alongside him as he flees from one deathtrap to another.

Some of those flights — particularly the spectacular chase sequences bookending the movie, one in London’s Waterloo Station, the other on the streets (and sidewalks) of New York — prove suitably spectacular. But it’s Greengrass’ ability to combine exhilarating action with a constant, weighty sense of dread that grounds "Bourne" and gives it a gravity, and a humanity, most action workouts lack.

The movie’s top-chop cast also keeps it real, with newcomer Strathairn proving an implacable foil for returnee Allen’s conscientious expertise.

As usual, however, it’s Damon who proves the key to this "Bourne’s" heart — and success.

Damon’s boyish, all-American openness provides an ideal contrast to Bourne’s murky, murderous past — and the deadly things he has to do to arrive alive.

The actor has said that this "Bourne" will be his farewell. And while one suspects audiences would follow him anywhere — including additional sequels — "The Bourne Ultimatum" proves that he’s smart enough to go out on top.