I'm just going to quietly regard the 2006 feature "School for Scoundrels" as a bad dream. While shooting itself in the foot with a cast of such world-renown, gut-bustin' jesters like Billy Bob Thornton and Jon Heder, "Scoundrels" more importantly wasted the talents of director Todd Phillips in a major way, casting serious doubts on his developing abilities as an ace comedic filmmaker. "The Hangover" restores faith in Phillips and the vulgar passions of the R-rated comedy, assembling a smutty epic of irresponsibility that handles with a certain amount of routine, but still delivers huge on laughs and knowing cringes.

On the eve of his wedding, Doug (Justin Bartha) is heading to Las Vegas with friends Phil the school teacher (Bradley Cooper), Stu the whipped (Ed Helms), and Alan the insane (Zach Galifianakis) for his bachelor party, planning a night of drunken debauchery. The next morning, Phil, Stu, and Alan awaken to find their suite trashed, no memory of the previous night's events, and Doug missing. Staggering around town, the trio attempt to piece together their rowdy celebration using the clues left behind: a stolen police car, an infant, a hospital admittance wristband, and Mike Tyson's pet tiger. Finding themselves in big trouble with an Asian gambler (Ken Jeong) and Doug's confused fiancée (Sasha Barrese), the guys scramble to locate their pal before their extensive path of destruction is discovered by their high-maintenance loved ones.

With "Road Trip" and "Old School," Phillips perfected a unique frat-boy/absurdist touch to his simplistic plotlines. He found humor through pitch-perfect performances and massive layers of ridiculousness, virtually unafraid to get a little weird on his audience through discomforting sexual exploits or raunchy circumstances of male bonding. After testing the romantic comedy waters with "Scoundrels" (and rewarded with lousy box office returns), Phillips returns to his dude comedy binky with "Hangover," and it's a lovely reunion. A spastic, whirlwind trip through blinding-daylight revelations and throbbing-headache disbelief, "Hangover" is a perfect vehicle for Phillips to run amok with hilarious disasters, casino misfortune, and extensive stupidity, rebuilding his wounded confidence with material that cherishes the art of the surprise.

It's Vegas; it's copious amounts of booze, women (Heather Graham shows up as Stu's new stripper bride), and troublemaking that comes to haunt our heroes when all they wanted was a night of freedom from their suffocating lives. The concept is wide open for the production to head anywhere it can possibly imagine, and through spirited performances from Cooper, Helms, and Galifianakis (perhaps playing uncomfortably close to his vacant stand-up comedy persona), "Hangover" profits from a fearless attitude that straddles the line between crude and nightmarish. The path to Doug frantically motors the trio all over the city, dealing with Tyson's animal demands (The Champ nabs big laughs playing his Phil Collins-loving self), random flashes of unlikely gangster violence, and their own bewilderment as they can't quite grasp the enormity of their evening, frequently stumbling over immeasurable trouble the mild-mannered guys can't believe they caused.

Actually, I think the less written about "The Hangover" the better. It needs to be experienced, not recalled. It's a film best valued as an extended surprise, with hilarity greatly enhanced by an atmosphere of the unanticipated, beautified by a soundtrack of goofy, ironic tunes to underscore any and all ludicrousness (though Phillips deserves a bravery medal for a forbidding Danzig opening title track). "The Hangover" is a hilarious adventure that makes Las Vegas feel reckless again (you don't sense that when Ashton Kutcher and Cameron Diaz are there, believe me). The film also recharges Phillips's creative batteries, reinforcing him as a top voice for silliness, especially when it comes to the dark fates of emasculated men.