Todd Phillips' The Hangover sets up a premise rife with comic possibilities, and damned if they don't exploit just about every single one of them. It's a ridiculously funny movie, yes--laughs from end to end, with so many good lines that even the day players get some. But it's also a skillful picture, blessed with an ingeniously constructed narrative that keeps the viewer involved while taking full advantage of its gifted cast and their specific comedic mojo.

Doug (Justin Bartha from those horrible National Treasure movies) is about to be married, so he zips off for a Vegas bachelor party with his best buddies Phil (Bradley Cooper) and Stu (Ed Helms). He also brings along his fiancé's brother, the odd (and frequently pantsless) Alan (Zach Galifianakis), for the ride. The quartet checks into Caesar's Palace (after a funny bit where Alan inquires if it was "the real" Ceasar's Palace--"Did Caesar live here?") and go up to the roof for toasts and Jaeger shots. Twelve hours later, they wake up in their trashed suite, in various states of nausea and undress; there's a chicken on the bar, a baby in the closet, a tiger in the bathroom, and Stu is missing a tooth. Oh, and Doug is gone.

The remaining three men spend the next day and a half trying to piece together exactly what the hell happened during their long blackout, and this is where Jon Lucas and Scott Moore's beautifully constructed screenplay really shines; instead of a blow-by-blow orgy of decadence, a la Very Bad Things, it's laid out like a murder mystery. They empty out their pockets to try to piece together exactly what happened when, and as they follow those "clues," it seems like the more they find out, the less they know. That central mystery, and their genuine concern for the well-being of their friend, gives the film a kind of frantic momentum that is missing from most comedies these days, even the good ones (like the charmingly shambling movies from the Apatow factory).

The casting is particularly good here; the three primary actors have terrific chemistry and play well off each other in unique ways. Cooper appears to be having a great time turning his earnest, nice-guy image on its head (to far greater effect than in his over-the-top villainous turn in Wedding Crashers). He's playing the most conventional character of the three, but it's not a simple "straight man" turn; he's reactively funny, in much the way Vince Vaughn was in Phillips' Old School. Helms charms in a performance that burrows deeper than the character's preppy, henpecked surface--he lets you see the party guy that lurks below, so you believe that he really would be friends with these guys (one problem with movies about old friends is that they frequently deal with such one-dimensional types, you can't understand what these people ever had in common). His manic takes and elaborate lies to his emasculating girlfriend are funny, and his impromptu piano tune is a highlight.

But Galifianakis is the break-out star, which is as it should be; he's been given the kind of role that you can't help but steal the movie with. As a diehard fan of his gonzo stand-up work, I've been saying for years that Galifianakis is the closest thing to Andy Kaufman we're gonna see in this decade; he's now got one up on his most clear influence, because Kaufman never made a movie worth a damn. Alan's odd demeanor and occasional non-sequiturs are reminiscent of his stand-up persona, but this is a unique and successful comic creation. Alan is just a little slow, and has an innocence about him, but he's also clearly up for anything--it's the kind of wide-eyed, mischievous man-child role that Belushi used to do so well. He's never off his game in The Hangover; even when he's not the focus of the scene, you're watching him react to whatever else is happening.

The rest of the cast is filled out with some solid, sturdy utility players. Jeffrey Tambor's presence is always welcome, it's nice to see Heather Graham (albeit briefly) in a movie that's premiering in theaters instead of on DVD, and Rob Riggle (from The Daily Show) and Cleo King ("Marcie" from Magnolia) have a very funny bit as the cops whose car has somehow ended up in the boys' possession. Hell, even the detestable Mike Epps gets a couple of laughs and appears briefly enough to keep from doing any real damage.

Phillips continues to immodestly begin his films with the title card "A Todd Phillips Movie" (as opposed to "film"), but his directing has become more confident (even after the misstep of School for Scoundrels). He does a terrific fake-out in the opening credits, starting with a snappy cover of "It's Now or Never" and credits rendered in a flowy, faux-wedding invite font, then switching to foreboding shots of the Vegas skyline and the grim music of Danzig. He doesn't let fancy camerawork get in the way of the jokes, but the film is inventively shot (I especially liked the overnight transition that covers the activity we don't see).

This is not to say that he doesn't occasionally stumble. There is one sequence that doesn't work at all, in which the guys question a doctor who treated Cooper during a hospital visit during their lost evening; the doctor inexplicably chats with the three guys (and the baby) as he performs a full (and I mean full) physical on a dumpy old man. We buy a lot of stretched premises in this movie, but I'm sorry, there's no reason in the world for this guy to let three strangers sit in on his physical, except so Phillips can get a cheap, mean laugh by showing us this poor old dude's bloated, wrinkly ass. This movie is better than that scene.

There are other bits here and there that don't quite work, but even taking those into account, there's an astonishing batting average of successful jokes in The Hangover--and I haven't even mentioned Mike Tyson, or the Rain Man parody, or the tiny naked Asian gangster. Just go see it, is the point. It's tight and fast and clicks along like a good watch--and it's funny as hell.

Jason lives in New York. He holds an MA in Cultural Reporting and Criticism from NYU.