Doug's younger sister Alex wasn't planning on tagging along on her brother's bachelor party. But thanks to her new sister-in-law, Alex is on the road to Vegas with the gang. But soon the night takes a turn for the worst. Alex and the guys wake up with a killer hangover, no recollection of what happened the night before, and what's worse: Alex's brother, the soon groom-to-be goes missing. With the help of the guys, Alex must retrace her steps to find out what exactly happened that night. Will they find Doug in time? You know what they say; what happens in vegas stays in vegas