Twenty years after the last installment of this slaughter-centric saga, we find the hulking John Rambo (Sylvester Stallone, inhabiting the role for the fourth time) retired from the world's political frays and working in the jungles of Thailand as a river-boat captain and snake-catcher for an onshore serpent circus, where the cobras and pythons he delivers are put through their snaky paces for the entertainment of whatever jungle tourists may happen by. This is an odd and hilariously unlikely occupation, but it's a living, presumably. And unlikeliness, of course, is the narrative water in which the whole Rambo enterprise wallows.

The plot, such as it is, is launched by the appearance of a Christian church group seeking Rambo's help in traveling upriver into neighboring Burma, where they intend to deliver medical help to the guerillas who've been fighting the country's homicidal military junta for the last 60 years. Contemplating this little evangelical band, who just want to change the world for the better, Rambo's face morphs from a sneer into a snarl, thus exhausting his entire emotional range.

"You bringin' any weapons?" he asks the group's leader, clearly a namby-pamby peacenik.

"Of course not!" the man responds.

Says Rambo: "You're not changin' anything."

But the group's lone female member (Julie Benz, the only unbutchered woman in the movie) pleads with him, and Rambo, regarding her in the unexpected way King Kong might contemplate a writhing sweetie clutched in his fist, finally agrees to put his river ferry at their service.

With this structural formality out of the way, the picture quickly descends into the familiar Rambo world of endless annihilation. Even in a cinematic age as murderous as our own, the movie is exceptionally violent. The explosions are red with gore and lumpy with flesh, and the limb-severing and skull-bashing are astonishingly graphic. In its vintage "Dirty Harry"-style emotional strategy, the bad guys -- the soldier-thugs of the Burmese government -- are so irredeemably vile (when was the last time you saw a crying infant tossed into a fire?) that we lust to wipe them out before Rambo actually gets around to doing so.

Stallone, the movie's writer and director as well as star, doesn't really look his 61 years. Slicked with dark grease and glowering beneath a nest of stringy black hair, he's as ageless as a boulder, and almost as expressive. The picture was filmed in Thailand, and its rainy murk is as oppressive as its non-stop brutality, which is monotonously undifferentiated -- someone or other is always being blown up or hacked to pieces, and that's that. Stallone's indifference to plot and feeling, and his unwavering commitment to carnage, has the quality of obsession. We start to wonder about his mental state. Not for long, though.

Check out everything we've got on "Rambo."

Visit [article id="1488131"]Movies on MTV.com[/article] for more from Hollywood, including news, reviews, interviews and more.

For breaking news, celebrity columns, humor and more -- updated around the clock -- visit MTVMoviesBlog.com.

Want trailers? Visit the Trailer Park for the newest, scariest and funniest coming attractions anywhere.