Zach Galifianakis

Zach Galifianakis arrives at the premiere of "The Hangover Part III" in Westwood. ( Jason Kempin / Getty Images / May 20, 2013)

Zach Galifianakis arrived at the premiere of “The Hangover Part III” on Monday night amid a throng of fans shrieking his name. “There’s a lot of Alan in it,” he reassured about his character's place in the film. “Hopefully he can sustain a movie. We will see.”

Indeed, the film revolves around the off-kilter Alan, who this time around is suffering from an early midlife crisis, sending the Wolfpack (Galifianakis, Bradley Cooper and Ed Helms) out on a road trip.

“He was the one stone left unturned," said director Todd Phillips, "and we thought we needed to solve him and make sure he’s OK. When he’s OK, we could finally move on because he’s the one that causes all the trouble.”

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The third installment, which opens May 23, should lift the franchise comfortably into the billion-dollar box office mark, after “The Hangover's" $400-million global take in 2009 and the sequel's more than $500 million worldwide two years later.

Galifianakis credits the success of the films to its archetypal characters resonating with audiences. Helms agreed that audiences can relate to it, despite the franchise's R-rated excesses.

“Who doesn’t know what a hangover is?” Helms said. “Everyone has intense personal experiences with hangovers, so I think it resonates on that level.”

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Galifianakis said the team didn’t set out to purposefully make an R-rated movie, but to simply make a comedy.

"The American audience has matured,” he said. “They’re just jokes. These movies are never politically correct. Political correctness in comedy does not mix well together.”

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Twitter:@DiangeleaMillar

angie.millar@latimes.com