Back in the summer of 2009, The Hangover came out of (virtually) nowhere to become a tentpole for raunchy, dark comedies. Brilliantly written and expertly directed, it was an instant smash, finishing the year at #6 and bringing in almost $300 million.

Two years later Part II landed with a thud (among critics, anyway– though I bucked the trend and enjoyed it), as many people complained it was just a half-baked rehash of the original. The comedy was still fast and furious, though, and Thailand proved to be the only place with more potential for debauchery than Las Vegas.

Now we finally arrive at the final part of the trilogy, and somewhere along the way writer/director Todd Phillips decided it would be a good idea to mess with the formula that had made him a household name. And comedy, apparently, is the first casualty.

The Hangover Part III arrives in theaters with all kinds of potential, but sadly this is yet another case of the trailer showing all the good parts and, frankly, giving away what could have been at least a few nice surprises. Playing more like a mafia flick or a crime caper, the film treats its comedy like a sporadic bonus instead of the backbone, and the result is a pretty hopeless mess.

On the bright side, there are no weddings or bachelor parties to speak of; the plot here is a road trip, as Stu (Ed Helms), Phil (Bradley Cooper), and Doug (Justin Bartha) try to take Alan (Zach Galifianakis) to a treatment center in Arizona. Along the way a beefy baddie named Marshall (John Goodman) runs them off the road, tells them how their old pal Leslie Chow (Ken Jeong) stole $20 million in gold from him, and then he kidnaps Doug. The Wolfpack is left with instructions to find Chow and deliver him (and the gold) to Marshall if they ever want to see Doug alive again.

After a brief stopover in Tijuana (where else, right?), the gang winds up back in Vegas where the promise of more mayhem awaits. This time around though the mayhem has lost its luster and never really gets going. Aside from a nifty sequence where Chow and the guys break into a Mexican mansion, the funniest part of the movie is a quiet scene capped by a series of looks between Alan and a pawn broker named Cassie (Melissa McCarthy, in the film’s best cameo).

There are no tasers, no face tattoos (Stu’s from Part II is conveniently gone without a trace here), and no stray tigers (though there is a decapitated giraffe and an asphyxiated rooster). In short, there’s just not much to laugh at. Where there is humor, sure, it’s very funny, but there’s just not much to laugh at.

I’m not sure whose decision it was to jettison the screenwriters of the original film, Jon Lucas and Scott Moore, from the second and third installments, but it may go down in Hollywood lore as one of the more boneheaded moves– along with stretching this thing into three parts in the first place. The trilogy that began with one of the most side-splittingly funny films of the last ten years has now come to an end with barely a weak chuckle.

2.5/5 stars