During a wild vacation in Las Vegas, career woman Joy McNally (Cameron Diaz) and playboy Jack Fuller (Ashton Kutcher) come to the sober realization that they have married each other after a night of drunken abandon. Not only that, but there is huge jackpot at stake. When an implacable judge freezes the prize money and refuses to grant an annulment, Joy and Jack are forced to try to make their impromptu marriage work.