Mortimer (Don Ameche) and Randolph Duke (Ralph Bellamy) are wealthy, bored and amoral commodity brokers in Philadelphia. When Billie Ray Valentine (Eddie Murphy), pretending to be a blind cripple, is caught and accused of stealing the briefcase belonging to their upper-class employee, Louis Winthorpe III (Dan Aykroyd), the brothers decide on a wager. They bet that the job makes the man and so arrange for Billy Ray and Winthrope to trade places. Billy Ray ends up with Winthrope’s house and job, partying with his friends from the ghetto. Winthrope ends up comedically penniless and homeless. They discover what the Dukes have done and decide to have a wager of their own. Billy Ray and Winthrope decide to trick the Dukes into losing their shirts on frozen orange juice futures. They are assisted by Ophelia (Jamie Lee Curtis), a street walker who has taken pity on Winthrope, and by Coleman (Denholm Elliott), Winthrope’s (and then Billy Ray's) butler. Through a series of hilarious adventures, the Dukes get their comeuppance and Billy Ray, Winthrope, Ophelia, and Coleman live happily ever after.