'The Hangover Part III' is "Alan's story".
Director Todd Phillips has revealed that the final installment in the buddy comedy series will centre largely on Zach Galifianakis' oddball character as he evolves and becomes less reliant on his friends Phil (Bradley Cooper), Stu (Ed Helms) and Doug (Justin Bartha).
He explained to ComingSoon.net: "To me, the key to this movie was that we wanted to tell Alan's story. It really felt like Alan's story was the loose end that needed to be tied up.
"That was the one person that we didn't know was going to be okay until we realize that he has met somebody who shares his own left-footed way that he lives. We realize that he's going to be alright and that's why it's the end. He is that loose thread."
As the franchise comes to an end, Phillips is sad to say goodbye to the trilogy but is still great friends with the cast, particularly Bradley Cooper.
He added: "I mean, Bradley is one of my best friends in the world now. I didn't know him before the first 'Hangover'. We've all traveled the world together, doing press and, of course, going to Bangkok [for 'Hangover Part II']. We've spent so much time together.
"I've laughed more in the last five years than most people do in a lifetime because of these movies. I just feel so incredibly blessed that I get to laugh all day every day and be around Zach and these guys."
'The Hangover Part III' is in cinemas on May 24.
Tagged in The Hangover Zach Galifianakis