The Hangover is a 2009 American comedy film directed by Todd Phillips, and written by Jon Lucas and Scott Moore. It is the first installment in The Hangover trilogy. The film stars Bradley Cooper, Ed Helms, Zach Galifianakis, Heather Graham, Justin Bartha, and Jeffrey Tambor. It tells the story of Phil Wenneck (Cooper), Stu Price (Helms), Alan Garner (Galifianakis), and Doug Billings (Bartha), who travel to Las Vegas for a bachelor party to celebrate the latter's impending marriage. However, Phil, Stu, and Alan wake up with Doug missing and no memory of the previous night's events, and must find their friend before the wedding can take place.