Not so Welcome to Las Vegas

Two best friends,their girlfriends, and their long term high school "friend", all plan to stay a couple weeks in Vegas for their friends 21st birthday. Drinks,gambling,sex,drugs, are all things that should be planned for their trip,but they aren't(at least not all of them). That all changes when a huge storm hits keeping them in Vegas,but the storm is not the only thing they should worry about,with a serial killer being searched for, This might not be the trip they were looking forward to after all.