"The Avengers"

3.5 stars

Rated PG-13 (intense sequences of sci-fi violence and action throughout and a mild drug reference)

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The hype has been building for years and it couldn't possibly be more deafening at this point.

After a series of summer blockbusters that individually introduced Iron Man, The Incredible Hulk, Thor and Captain America, all these characters come together alongside several other friends and foes in "Marvel's The Avengers."

And with director and co-writer Joss Whedon, they couldn't be in better hands. He's pulled off the tricky feat of juggling a large ensemble cast and giving everyone a chance to shine, of balancing splashy set pieces with substantive ideology. Stuff gets blowed up real good in beautifully detailed 3-D in "The Avengers" - the area in and around Grand Central Terminal, for example, gets obliterated beyond recognition in an exhausting, climactic battle - but the film as a whole is never a mess from a narrative perspective.

Whedon keeps a tight rein on some potentially unwieldy material, and the result is a film that simultaneously should please purists (one of which he is) as well as those who aren't necessarily comic-book aficionados. He also stays true to the characters while establishing a tone that's very much his own. As he did with the recent horror hit "The Cabin in the Woods," which he co-wrote and produced, Whedon has come up with a script that's cheeky and breezy, full of witty banter and sly pop-culture shout-outs as well as self-referential humor, one that moves with an infectious energy that (almost) makes you lose track of its two-and-a-half-hour running time.

The back-and-forth between Robert Downey Jr.'s glib Iron Man and Chris Evans' old-school Captain America is electric, while Downey's more low-key, philosophical exchanges with Mark Ruffalo's Hulk help give the film some intellectual heft. Actually, Downey damn near runs away with this whole thing, a tough feat to pull off in a cast full of personalities who are literally larger than life; it just goes to show once again how irresistibly charismatic he can be with the right kind of writing.

But the film's vibe is never smug or off-putting; these are still comic book heroes full of all the torment and introspection you'd expect. And for a movie that's violent as hell, "The Avengers" ends up being an earnest plea for peace. As in the best of its predecessors, the original "Iron Man" from 2008, it's a reminder that a summer blockbuster can be glossy and entertaining but still have meatier matters on its mind.

And we haven't even gotten to the plot yet: It's your basic bad-guy-wants-to-take-over-the-world kinda thing. But even Whedon seems to recognize what a hackneyed premise that is, so he has a little fun with it.

The preening, effete Loki (Tom Hiddleston), the bitter brother of hunky demigod Thor (Chris Hemsworth), descends to Earth from Asgard, which still has a distinctly '70s cheesiness about its twinkly sci-fi aesthetic. Once here, he steals the Tesseract, the cosmic blue cube that gives its bearer unlimited power, or some such.

The no-nonsense Nick Fury (Samuel L. Jackson), the head of S.H.I.E.L.D. - which had been entrusted with the safety of said cube - springs into action to reacquire it by assembling a dream team of superheroes and other sundry bad-asses with specialized skills. Nick gets help in this endeavor from his right-hand man, Agent Coulson (Clark Gregg, once again bringing some welcome deadpan humor to this outlandish scenario).

Besides Iron Man, Thor and Captain America, The Hulk's services are needed because the Tesseract exudes a radiation that will help track it, and The Hulk - despite the threat of his gigantic, green volatility - knows a little something about gamma rays. (Ruffalo, stepping into the Bruce Banner role that Eric Bana and Edward Norton played previously in the past decade, brings a sense of wry bemusement and appealing self-deprecation to this dangerous and misunderstood character.) There's also master assassin Hawkeye (Jeremy Renner) and super spy Black Widow (Scarlett Johansson).

But because these are superheroes with super powers, they also have super egos. And so a great deal of time is spent having them talk a lot of trash and square off against one another to prove who's toughest. There's Iron Man vs. Thor, Thor vs. The Hulk, Hawkeye vs. Black Widow and so on. While they might seem like filler, these showdowns allow each character to have his or her time in the spotlight, and they do build genuine tension. They also happen to represent the adolescent fantasies of every geek in the audience. So in theory, everyone's happy.

Eventually they will all have to come together for one epic battle against their shared enemy in Midtown Manhattan, home of Iron Man Tony Stark's latest dazzling architectural creation, his eponymous high-rise, and a cool place in general to stage massive movie destruction. Much of the gadgetry is cleverly detailed, as you'd expect - Tony Stark has devised stunningly efficient ways to get his metal suit on and off - but "The Avengers" is at its strongest in its quieter, simpler moments - when people are actually talking to each other.

The dialogue sparkles as brightly as the special effects; these people may be wearing ridiculous costumes but they're well fleshed-out underneath. And so in every regard, this movie truly fulfills its hype.