Bradley Cooper as Phil Wenneck
Ed Helms as Dr. Stuart Price
Zach Galifianakis as Alan Garner
Ken Jeong as Leslie Chow
Heather Graham as Jade
Jeffrey Tambor as Sid Garner
Justin Bartha as Doug Bilings
John Goodman as Marshall
Gillian Vigman as Stephanie
Sasha Barrese as Tracy Bilings
Jamie Chung as Lauren Price
Mike Epps as Black Doug
Melissa McCarthy as Cassandra
When most sequels get made, you usually end up with one of two possible flavors. You could get a complete recreation of the plot of the original with a few nominal changes (new environment, new McGuffin, etc.). Or you could get a new plot with little to no connection to the first except for the characters and one or two other well-known details (old environment, old McGuffin, etc.). Director Todd Phillips has now tried both of these flavors to keep "The Hangover" franchise afloat and all he's managed to prove was that he shouldn't have bothered in the first place.
While "The Hangover Part II" went route one, Phillips has gone route two this time around as the Wolfpack (Cooper, Helms, Galifianakis) gather together to take man-child Alan to some sort of retreat to help him finally grow up following the death of his father (Jeffrey Tambor). Which, "Hangover" fashion, quickly goes off the rails as they are forced off the road by a malevolent drug dealer (John Goodman) who wants to use Alan to find everyone's favorite high-voiced hell raiser, Chow (Ken Jeong).
If you're waiting to hear where the Hangover part of the plot comes in, you'll be waiting a long time. There is one eventually, but really this film is just about taking our familiar cast of characters and sending them back to a familiar location so that they can encounter a bunch of people they've encountered before.
Actually, putting these guys in a brand new plot is a good idea, there's nothing worse than repetition even if that is the bread and butter of sequels. Unfortunately, somewhere along the lines, Phillips (now also a co-screenwriter) has decided that Cheong and Galifianakis are the two best things about the franchise and any film that is going to work needs to focus on them as much as possible. So if you like those characters a lot and laugh at anything they say and do, "Hangover Pt III" will definitely work for you.
The problem is there's not much else holding it together and no one else who seems particularly interested in trying. With so much of the focus on Alan and Chow, everyone else--including the other Wolfpack members--gets pushed to the background most of the time with little to do but react in horror as they set on by Chow's malevolent fighting roosters or try to break into a drug dealer's Tijuana retreat to retrieve some stolen gold.
Part of that is because even Phillips must realize there's nowhere else for any of these characters to go--Phil and Stu have done a fair amount of growth over the last two films--and all we're interested in is seeing them do their old thing again.
But at least they're doing better than Bartha, who gets maybe 10 lines of dialog this time around before having a bag put on his head.
It does have its funny moments, don't get me wrong. Phillips still knows how to put together a well-rendered sight gag, no matter how obvious the payoff will be. The opening gag with Alan driving a giraffe down a Los Angeles freeway is as well put together as anything he's attempted in all three films.
Away from that is a different story and eventually it becomes obvious he doesn't really know what to do, so he's going to keep thrusting an insane Chinese drug dealer at us. Because that will never get old, right?
Eventually of course they do have to go back to Las Vegas because they're in the US so what else are they going to do? Which means naturally running back to many of the hallmarks of the first film like Caesar's Palace, where at least Helms and Cooper get to do something even if it's not particularly funny.
And even then, it just keeps going and going and going.
These movies are done. They are past done. Yes, "The Hangover" was a genuinely funny movie, but the warm feelings towards a well done piece of entertainment are not enough to make "Part III" anything more than rote. If your sense of humor is similar to Phillips', you will probably like it. Otherwise, it's just a slog, and hopefully one we never have to go through again.