The Hangover is a 2009 American comedy film directed by Todd Phillips. The movie follows the story of three friends, Phil (Bradley Cooper), Stu (Ed Helms), and Alan (Zach Galifianakis), who wake up after a wild bachelor party in Las Vegas with no memory of the night before. As they try to piece together what happened, they discover that they have lost their friend Doug (Justin Bartha) and must find him before his wedding.