The trailers and TV spots suggest it’s just another beer-and-boobs, party-hearty farce, but “The Hangover” is surprisingly clever as well as R-rated rowdy. At once raucously free-wheeling and meticulously contrived, pic satisfies as a boys-gone-wild laff riot that also clicks as a seriocomic beat-the-clock detective story. Reviews and word-of-mouth could help this profanely funny comedy exceed expectations and achieve the status of breakout hit. Homevid biz should be equally impressive after a leggy summertime theatrical run.

Helmer Todd Phillips (“Old School,” “Road Trip”) grabs attention right from the get-go with an edgy-funny prologue that triggers an extended flashback. It’s a smart move, in that the vaguely foreboding intro adds an intriguing undercurrent to the comedy in otherwise ordinary (if not generic) expository scenes.

Two days before he ties the knot with his rich and gorgeous fiancee, blandly affable Doug (Justin Bartha) takes off for a brief Las Vegas sojourn with three groomsmen: His two best buddies — Phil (Bradley Cooper), a cynical and sardonic high school teacher, and Stu (Ed Helms), a dentist usually kept on a tight leash by his nagging girlfriend (a truly monstrous Rachel Harris) — and Alan (Zach Galifianakis), Doug’s future brother-in-law, a lumpy lunk who’s all too eager to befriend and belong.

Even with odd-man-out Alan along for the ride, the bachelor-partiers enjoy a wild night of booze-fueled revelry in Sin City. The next morning, however, three of them awaken in their posh hotel suite with only the haziest of memories about the previous evening’s events, and no explanation at all for the snarling tiger in their bathroom and the crying baby in their closet.

Worse, they have no earthly idea what happened to the inexplicably missing Doug.

Exhibiting an ingenuity one might not expect from the same writers who gave us “Four Christmases” and “Ghosts of Girlfriends Past,” scripters Jon Lucas and Scott Moore provide one uproarious pay-off after another as the groomsmen frantically scramble to retrace their steps so they can reconnect with the misplaced (or, quite possibly, waylaid) groom.

Their circuitous journey brings them in contact with, among others, Taser-wielding cops, angry Asian gamblers, a perky stripper (a chipper Heather Graham) with newly forged ties to Stu, and an unexpectedly equanimous but not infinitely patient Mike Tyson (played, in a bold stroke of casting, by Tyson).

Early on, it’s revealed that the revelers weren’t merely drunk, they were drugged while cutting an antic swath through the Vegas night world. Oddly enough, that’s just enough to anchor the pic in something like real-world logic, even as the plot takes ever more outlandish twists and turns. In fact, it’s tempting to read “The Hangover” as a wild-and-crazy spin on a scenario that would have been entirely suitable for a deadly serious ’40s film noir.

The humor is unapologetically raunchy — a closing-credits photo montage includes some borderline NC-17 naughtiness — and sporadically brutal. Helmer Phillips sustains an overall tone of anything-goes swagger that he neatly subverts with steadily mounting desperation and ego-deflating humiliations. Throughout it all, however, Cooper, Helms and even Galifianakis (whose character comes closest to caricature) remain sufficiently disciplined to refrain from going too far over the top.

Bartha does well in a thankless role, but he’s simply not visible long enough to make as much impact. On the other hand, Ken Jeong makes the absolute most of his limited screen time as an effete antagonist whose mincing trash talk likely will be quoted extensively by the pic’s fans.

Lenser Lawrence Sher does an excellent job of subtly enhancing the sense of danger lying just below the comic surface. Other tech credits are fine. Jokey references to “Rain Man” and “A Beautiful Mind” are amusing, but not nearly as funny as the pic’s self-aware reference to the cliched notion that there’s nothing as hilarious as a pratfall by a fat man.

The Hangover

  • Production: A Warner Bros. release and presentation in association with Legendary Pictures of a Green Hat Films production. Produced by Todd Phillips, Dan Goldberg. Executive producers, Thomas Tull, Jon Jashni, William Fay, Scott Budnick, Chris Bender, J.C. Spink. Co-producers, David A. Siegel, Jeffrey Wetzel. Directed by Todd Phillips. Screenplay, Jon Lucas, Scott Moore.
  • Crew: Camera (Technicolor), Lawrence Sher; editor, Debra Neil-Fisher; music, Christophe Beck; music supervisors, George Drakoulias, Randall Poster; production designer, Bill Brzeski; supervising art director, Andrew Max Cahn; art director, A. Todd Holland; set decorator, Danielle Berman; costume designer, Louise Mingenbach; sound (Dolby Digital/DTS/SDDS), Lee Orloff; assistant director, Jeffrey J.P. Wetzel; casting, Juel Bestrop, Seth Yanklewitz. Reviewed at AMC Studio 30, Houston, May 20, 2009. MPAA Rating: R. Running time: 99 MIN.
  • With: Phil - Bradley Cooper Stu - Ed Helms Alan - Zach Galifianakis Doug - Justin Bartha Jade - Heather Graham Tracy - Sasha Barrese Sid - Jeffrey Tambor Mr. Chow - Ken Jeong Melissa - Rachel Harris Mike Tyson - Himself Black Doug - Mike Epps