I'm starting to believe that comedy and sequels simply do not mix.

It is no coincidence that horror, the other genre I believe this about, works because of the same sort of involuntary reactions that make great comedy effective.  It feels to me like the simple act of making a sequel to a comedy or a horror film is an act of diminishing returns in practice.  There is an element of surprise that seems necessary for comedy or horror to work on an audience completely.  The first "Hangover" became an international hit based on two things:  the chemistry of its cast and the clever way the film was structured as a mystery.  That allowed for the film to drop its best surprises out of chronological order, and it saved its biggest payoffs for the closing credit photo montage.

"The Hangover Part II," opening tomorrow, is a well-made sequel.  Once again, Todd Phillips seems to be one of the few guys making this sort of big broad mainstream comedy who loves to shoot in full 2.35:1 scope, and he's got a keener sense of what to do with a frame than, for example, Rob Marshall in "Pirates of the Caribbean 4," who shot the jungles of Hawaii like he was making a TV movie on a soundstage in Burbank.  Phillips takes full advantage of the grimy, sweaty opportunities afforded by Bangkok and Thailand, and the film has this dangerous, sun-blasted visual style that really works.  The cast all seem game for this return to the characters, and there's a manic energy to a lot of it that seems appropriate.

I just wish I thought the damn thing was funny.

To be fair, I think they made exactly the film they set out to make.  I don't believe the movie does a bad job of telling the jokes it wants to tell.  I just don't think Todd Phillips seems terribly interested in jokes of any kind.  The same was true of his last film, "Due Date," as well.  This sequel, co-written by Phillips and Craig Mazin and Scot Armstrong, is more about attitude than clear set-ups and punch-lines.  It's a choice that seems very intentional, especially when you consider the structure of this movie.  This is not just a follow-up to the first film; it is a structural remake.  By building the film to resemble the first film so closely, Phillips is setting the audience up.  That way, every time he makes you think you know what's about to happen and he does something else, he's aiming to elicit that surprise, that involuntary reflex that is so crucial to comedy.  It is a specific gamble, and when you make a sequel that serves to comment on the way the first film was structured, you can either end up with a lifeless Xerox like "Home Alone 2: Lost In New York," or you can end up with something as clever and sharp as "Back To The Future 2."

As with the first film, Alan (Zach Galifianakis), Stu (Ed Helms), and Phil (Bradley Cooper) are getting ready for a wedding when they lose a full night to partying, only to wake up missing someone, unable to remember the previous night, and in trouble.  The film is structured as a mirror of the first, and the laughs, such as they are, come from that recognition instead of surprise this time.  The main thing this film does is turn up everything that the first film did.  Bangkok is a far more dangerous city than Vegas, and Phillips seems so determined to punish these characters this time around that I started expecting at least one of them to die.  Stu, in particular, gets abused mightily this time, and there's just something about Ed Helms that almost invites it.  His character was the one most traumatized by the events of the first film, and he's so scared at this point of being roofied again that he won't even drink something unless it's sealed.

He's right to be scared, of course.  And by the time the guys are drugged and kick off their long night of terrible choices, they've already made a number of terrible choices that all but guarantee things will go badly for them.  They're so aggressive about making their mistakes that I feel like we can't root for them this time out.  If you've gone through what they go through in the first film and you still screw up this badly, you're asking for it.  In particular, if you invite Alan to be part of anything, you're asking for it.  Zach plays Alan as even more of an unhinged sociopath this time, and his obsession with Billy Joel aside, I don't think the character is funny.  I think he's a nightmare, and there's no way I'd ever include him in any event in real life.  I know… he has to be included or there's no movie, but when the movie is so mechanical in the way it puts the cast back together, it makes it harder for me to invest and to laugh.  In the first film, they all felt trapped by circumstance, but in this film, they made these circumstances.  It's hard to feel sympathy for someone who basically dares bad things to happen to them.

Monkeys, tattoos, silent monks, and gender-challenged lady boys are just part of the long night that Alan, Stu, and Phil have to piece together as they try to find Teddy (Mason Lee), the younger brother of Stu's bride-to-be, the gorgeous Lauren (Jamie Chung).  Considering they start the day by finding his severed finger, there is a surprising lack of urgency to their big frantic day.  It all seems fairly easy, all things considered.  Bringing back Ken Jeong as Mr. Chow makes no sense at all, and his introduction in the film has got to go down as one of the most oddly grotesque introductions of a character in a studio movie ever.  I'd be down with the envelope-pushing filthy if it paid off in dark laughs, but it doesn't feel like it does.  It's too scatter-shot, too concerned with paying homage to the first film's jokes to ever really feel like it has a pulse of its own.

I don't hate "The Hangover Part II" the way I hated "Pirates 4," but I find myself hard-pressed to recommend it, either.  I'd rather see Phillips moving forward than marching in place like this, and I can't imagine audiences are going to feel as passionately about this one as they did about the original.  At least seeing this helped me crystallize my own feelings about comedy sequels in general, so I got something out of the two hours in the theater.  Even so, it's no fun to report that this one is so perfunctory, so deeply routine even as it struggles to feel unhinged.

"The Hangover Part II" opens in theaters nationwide tomorrow.