What Happens In Vegas stars Cameron Diaz and Ashton Kutcher as Joy and Jack two strangers who wake up together to find that they've gotten married following a night of debauchery in Sin City. To make matters worse one of them has won a huge jackpot after playing the other's quarter! The newlyweds devise ever-escalating schemes to undermine each other and get their hands on the money - only to find themselves falling in love amid the mutual backstabbing.