The Hangover is a 2009 American comedy film, co-produced and directed by Todd Phillips and written by Jon Lucas and Scott Moore. It is the first film of 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, Stu Price, and Alan Garner, who travel to Las Vegas for a bachelor party to celebrate their friend Doug Billings' impending marriage. However, Phil, Stu, and Alan have no memory of the previous night's events and must find Doug before the wedding can take place.