Grossing an astounding $277 million in the domestic box offices, the first “Hangover” film was one of the most successful films of summer 2009. By far the highest grossing R-rated comedy of all time, “Hangover” is the third highest R-rated film to boot. It's guaranteed that its sequel, “The Hangover Part II,” which comes out today, will follow suit.

Although director Todd Phillips and star Zach Galifianakis stumbled last year with the atrocious “Due Date,” they’re both in fine form for the second “Hangover” film, the rare sequel that bests its predecessor in nearly every way.

The sequel's plot is nearly identical to the first film – Stu (Ed Helms), Phil (Bradley Cooper) and Alan (Zach Galifianakis) drink to excess before a wedding and wake up hours later to discover one of their friends missing. This time around, instead of trying to find the missing groom in Vegas, they’re searching for the brother of Stu’s bride-to-be while stranded in Bangkok, Thailand.

For much of the first 20 minutes, the film is painful to watch. We’re quickly reintroduced to all the characters, which mostly involves Galifianakis being standoffish and Helms playing easily flustered. There’s an extensive collection of wedding cliches, complete with a resentful future father-in-law, an awkward speech at a rehearsal dinner and zany cultural clashes that are uninspired and unfunny across the board.

Audiences brave enough to stick around after the dispiriting first act devoid of humor will find plenty to like once its characters find themselves in a dingy Bangkok hotel room with no memory of how they got there. Just like the first film, most of the entertainment comes from watching the three heroes stumble their way through the previous night’s events, which are suitably more destructive than the first film’s mishaps, even reducing an entire city block to smoldering ashes.

Because Vegas seems relatively innocuous next to the crime-ridden Bangkok, the film has a sense of danger and urgency that further ups the ante. The stakes are raised across the board and there’s a sense of urgency to the group’s quest that was missing from the first film.

The sequel also escalates the comedy, venturing to weird, dark places for laughs. A short sequence in a strip club that’s not what it appears is perhaps the film’s oddest detour, made utterly hilarious by Ed Helms' increasingly horrified reactions.

Helms supports most of the film. The always funny Galifianakis gets most of the film’s big laughs, but Helms delivers plenty of solid, chuckle-worthy one-liners and tears into the film’s brief dramatic moments with aplomb. He even manages to sell a climactic speech that could have been unbearably cheesy with a weaker actor.

Fans of the first “Hangover” film know what they’re getting into with “The Hangover Part II.” This is essentially the same film, but even more over-the-top and surprisingly better. Despite a few dead spots in the beginning, it's a worthy sequel; a memorable R-rated comedy that dares the audience to give it enough money to warrant a third film.