The once and future action hero Sylvester Stallone delivers 9/10 of a taut, sobering, bloody thriller about the futility of trying to change people in Rambo, which opened nationwide on Friday. Director, co-writer and star Stallone has it in him to make a penetrating, multi-layered story that isn't afraid to look at the dark side of Vietnam vet turned murderous killing machine John J. Rambo. But in the end, just like Rambo, Stallone can't help being true to himself.

The fourth film based on a character originally created by novelist David Morrell in 1972, the newest edition posits that Rambo has returned to Thailand after his adventures in Afghanistan in Rambo III. Nearly 20 years have passed in real life, but in the film the time period is left unspoken. News footage refers to a breakdown in nearby Burma -- a country that officially changed its name to Myanmar in the late 1980s -- and atrocities being committed by the military against defenseless villagers. Whatever the year, Rambo has settled back into a peaceful lifestyle. He hunts snakes for a living and has lost any spiritual or political beliefs he might have once held.

When a Christian missionary relief group seeks to hire his fishing boat for a trip up river to deliver Bibles and medical supplies, he initially refuses. Michael Burnett (Paul Schulze), the group's leader, is earnest and stiff, imploring Rambo to help because they believe they can change people's lives. Rambo asks, "Did you bring weapons?" "Of course not!" Rambo replies, "Then you're not changing anything." Thus the seed is planted for a classic confrontation between good and evil.

Rambo's resolve is quickly broken by Sarah (Julie Benz), Michael's apparent girlfriend and the only woman in the group. (When the others are never even introduced by name, we quickly surmise that they are present merely to serve as cannon fodder.) Daybreak finds the little group puttering up river with Rambo at the helm. That night, they try to glide past an encampment of Burmese pirates but are discovered and Rambo must kill all the bad guys to save the group, a decision that does not sit well with Burnett and shocks Sarah.

The group provides medical aid and ministers to a village until a particularly evil unit of the Burmese army arrives to rain down death and dismemberment upon the poor farmers. The scene is incredibly brutal, as the soldiers rampage through the village, shooting defenseless men, women, and children at point blank range, slashing off limbs at will, and generally behaving as the most savage band of bastards on the face of the earth. The unit's leader proclaims his message to the very few survivors: 'I am here to inspire fear.'

Somehow Sarah, Michael, and at least two others members of their group survive and are taken prisoner. A senior member of the group (Ken Howard) arrives in Rambo's modest living quarters ten days later, asking for his help. The Christian group has hired a band of mercenaries, which needs Rambo to guide them to the point where he dropped off the relief workers. Before you know it, Rambo is back in action, effecting another rescue against all odds.

The first Rambo film, First Blood, was surprisingly effective on a variety of counts. Set in the gloomy, forested Northwest, a tense atmosphere was created by simply waiting for Rambo to explode into action. He was a man of few words, but Stallone had a thousand-yard stare (referenced in the new film) like no other, and demonstrated ingenuity in setting up traps for the police officers and National Guardsmen who were foolish enough to try and capture him. (I haven't read the original novel, though reportedly the film takes extended liberty with the character, converting him from vicious villain into tortured hero.) Rambo was the epitome of the Reluctant Warrior; he just wanted to be left alone, and only when push came to shove did he go so far as to defend himself.

The sequel, Rambo: First Blood Part II, plucked the character out of prison and sent him back to Vietnam on a P.O.W. rescue mission. Stallone as Rambo, with his hyper-inflated musculature, bandana, and prowess with knives, machine guns, and a bow and arrow, came to represent militant American jingoism. The message to the peaceniks was clear: "If you hippies had let us fight the war the way we wanted, we would have won Vietnam." It was historical revisionism of the worst sort, but it struck a powerful chord in Reagan's America.

Rambo III was driven more by the financial success of its predecessor than anything else; it made money because of Stallone's global star power and the studio's ability to market wholesale slaughter and violence -- and helicopters, don't forget the helicopters.

In the latest film, Stallone invests Rambo with a non-denominational, apolitical cynicism, which taps into the overwhelming feeling that many people have today: no matter what you do, nothing will ever change. That flies in the face of the campaigns of several Presidential candidates, who promote themselves as agents of change.

In Rambo's world, he knows that nothing will change: he doesn't help the relief group because he thinks they can do anything to help the Burmese people, he helps them because he's moved by Sarah's fervent optimism. He doesn't charge out to rescue the group, he prepares himself to save Sarah.

Something within him has changed, though. It's not only the nightmare he suffers just before being recruited for the rescue mission -- a terse black and white recap of Rambo's previous cinematic missions -- it's a realization that he's responsible for what he's done in his life. In itself, it's startling to see Rambo take responsibility for his own actions, instead of blaming others for forcing him to do things he doesn't want to do.

When that realization hits, he's ready to die, an attitude he explicates when he comes into conflict with the mercenaries: "Live for nothing or die for something." Rambo is ready to take up life again in human society.

The following may constitute a SPOILER, so if you'd like to avoid knowing more, please come back after you've seen the film.

For everyone else, I'd like to go on the record and say that I normally try to avoid spoilers, but in this case it's the only way to explain why I feel the film ultimately falls short.

Ready to continue despite the SPOILER AHEAD?

Okay.

To get there, of course, he must first rain down an equal amount of death and dismemberment upon the evil Burmese army unit, which he proceeds to accomplish in an extended orgy of righteous kills that surely must rank among the most explicitly violent in recent mainstream cinema. The miscalculation here is that the sequence is so outlandishly extreme in its violence that it appears to cancel out all the thoughtfulness that has come before.

It's as though Stallone suddenly looked up and said to himself, "Wait a minute, what am I doing, being all meditative and engaging in quiet executions camouflaged by rain and vegetation? I'm Rambo! I need to make people [i.e. the otherwise powerless audience] feel good about themselves by viewing me as a surrogate to work out their own anxieties by blowing the living hell out of dozens of bodies. And killing all the bad guys is the duty of every American."

That final sequence elicited several cheers from the crowd at the morning screening I attended. I don't mean to oversell the virtues of the film up to that point, but I felt Stallone was really on to something, and then gave in to his baser instincts to bring back the Rambo that many people knew and loved: the 80s action hero mowing down the bad guys without mercy.

If you saw any of the early trailers and were surprised at the level of violence, well, nearly all those shock shots are in that final battle sequence. It's what will sell the picture, and if it wasn't there I'm sure some would have complained that Rambo had wimped out. For me, it felt out of character and out of tone with what came before.

Stallone clearly knows how to direct an effective action picture. For the most part, he eschews the fast-cutting, blitzkrieg style of editing, which makes it easy to follow the intricate choreography of the scenes. Of course, we only get to know Rambo, Sarah, Michael, and a couple of the mercenaries, so it's difficult to care about the fate of so many faceless victims, yet the early attack on the defenseless village is devastating.

And, for good and for bad, that final battle sequence will get people talking.