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. Besides that, there is a huge jackpot at stake. An implacable judge freezes the prize money and refuses to grant an annulment, so Joy and Jack must try to make their impromptu marriage work.