You can never keep a good man down, even when the man himself is gone. That seems to be the operative idea behind “The Bourne Legacy,” in which Jeremy Renner replaces Matt Damon as a super-secret operative on the run from agents of his own government. The directors of the previous three installments, Doug Liman and Paul Greengrass, are missing this time around as well, replaced by Tony Gilroy, who co-wrote all the earlier entries in the series as well as this one and helmed “Michael Clayton” and “Duplicity.” Their absence, unfortunately, proves a serious drawback.

The premise of the script by Gilroy and his brother Dan is that Jason Bourne wasn’t the only product of US programs to train highly sophisticated, specially endowed assassins; the national security apparatus had a whole slew of such projects on line, and Bourne’s very public shenanigans (this story is occurring simultaneously with that of “The Bourne Ultimatum,” as we see in periodic news flashes about the fugitive Jason) threaten to reveal them all to public—and congressional—scrutiny. So shadowy chief intelligence honchos Eric Byer (Edward Norton) and Mark Turso (Stacy Keach), along with the CIA director (Scott Glenn), decide to purge the record of their existence by literally wiping out everybody who could spill the beans. That includes a snoopy English journalist, all the scientists involved in the top-secret work that brought the projects to fruition, and the agents themselves. It may be a dirty business, but Byer justifies it in the name of patriotism—at one point he describes himself as a national “sin eater,” having to do immoral things for the greater good.

This being a government operation, however, it doesn’t go as planned. One of the scientists who was supposed to be disposed of in an orchestrated “workplace massacre”—the lovely Dr. Marta Shearing (Rachel Weisz)—escapes the slaughter, and when agents later come to her home to stage her supposed suicide, she’s saved by an even more troublesome survivor—Aaron Cross (Renner), the last of the “Outcome” operatives who were cousins of Bourne’s “Treadstone” group. The difference is that the Outcomers are endowed with enhanced mental and physical abilities through regular doses of special pills (or “chems,” as they term them) provided by Shearing’s pharmaceutical firm; and Cross, who evaded a drone that had his name on it, has searched Shearing out in order to get more of the drugs he needs, rescuing her from her would-be assassins in the process. But she informs him that the only place that houses the virus with which she can make his powers permanent is the company facility in the Philippines, so the two are soon off to Manila.

Up to this point the movie has had some big action scenes—the drone attack on Cross in Alaska, the mass killing in Shearing’s science lab, Cross’s rescue of the pretty doctor—and they’re all staged reasonably well. But for the most part it’s consisted of rather slow, confused expository material, doled out in bits and pieces designed to keep the audience more confused than engaged, and Renner’s morose scowl and flat line delivery haven’t made it any more engrossing. Now it turns into a rather tedious long-distance chase, as Byer and his minions use surveillance footage, satellite photos and computers to figure out where the pair is headed while the fugitives forge documents, make travel arrangements and coordinate their schedules to get to their destination. Arriving in Manila but a step before their pursuers, they achieve their objective with the drugs, but not without causing a mini-riot and becoming a target of the police. That sets the stage for a culminating chase on foot and wheels that leaves the crowded city and its unlucky pedestrians far worse for wear.

One of the curious things about this prolonged final-reel set-piece is that while Gilroy goes to inordinate lengths to detail how Byer and his crew track Cross and Shearing to Manila with all their technical equipment, he’s mum about how the local police locate their hiding place in the massive metropolis with little apparent difficulty. Another is that the cops aren’t the only ones pursuing them: Byer summons from deep cover an even more advanced super-assassin (from another program called “LARX”) to take them out, a fellow who can apparently detect them by their scent (but ends up merely following the police to their hideout—a bummer). Since Byer is systematically deleting all the government’s Bourne-like comrades (after all, only Treadstone is really in jeopardy, but Outcome is targeted as well, so presumably all similar projects would join them), one has to wonder why bloodhound-man had been spared. In the end it doesn’t matter much, though, since he proves about as effective at his job as the Terminator was in killing John Connor, though in fairness it must be added that he does cause about as much mayhem. Unfortunately, the big chase with which the movie concludes is so messily choreographed that it’s likely to elicit more snickers than thrills.

Throughout Renner proves an inadequate substitute for Damon; he’s an accomplished actor, as “The Hurt Locker” demonstrated, but his dour, serious manner doesn’t really jibe with action roles like this one or his recent turn in the latest “Mission Impossible”—meatier dramatic parts would be more suitable. Norton, an equally fine actor, is similarly out of his element here. The part of the snarling, single-minded intelligence chief makes no demands on his talent, and he responds with a pretty anonymous turn. Of the leads Weisz comes off best, but that’s not saying much, and the supporting cast—including a few stalwarts from previous installments—is reliable (though Albert Finney looks in terrible physical shape in his single scene). But no one really has a chance to shine.

That’s because Gilroy seems more interested in the intricacies of his plot and the gadgets he’s written into it than the human dimension; the actors are little more than cogs in the narrative machine he’s constructed. Still, except for that chaotic Manila chase, he, stunt coordinator Chris O’Hara and cinematographer Robert Elswit manage the action sequences decently enough to make you wish there were more of them, even if editor John Gilroy (another brother) hasn’t always cut them with the greatest finesse. James Newton Howard’s score is conventional boom-boom stuff.

One can understand Universal’s desire to extend what’s been a very successful franchise, but “The Bourne Legacy” will come as a major disappointment for those who enjoyed the earlier trilogy, a mostly plodding chase movie that revs up too infrequently and then not always excitingly. Of course the Bond series has had its share of clunkers too, but if the inevitable sequel proves as flat and disjointed as this, people might start referring to “The Bourne Plague” instead.