Two days before his wedding, Doug (JUSTIN BARTHA) and his three friends (BRADLEY COOPER, ED HELMS and ZACH GALIFIANAKIS) drive to Las Vegas for a blow-out bachelor party theyll never forget. But, in fact, when the three groomsmen wake up the next morning, they cant remember a thing. For some reason, they find a tiger in the bathroom and a six-month-old baby in the closet of their suite at Caesars Palace. The one thing they cant find is Doug. With no clue as to what transpired and little time ...