A wealthy commodities broker, Louis Winthorpe III, lives a life of privilege in Philadelphia, enjoying the benefits of his position at Duke & Duke, a prestigious trading firm run by the unscrupulous brothers Randolph and Mortimer Duke. His life is the polar opposite of Billy Ray Valentine's, a street-smart hustler who barely scrapes by through petty cons. The two men's worlds collide when the Dukes, in a callous bet on nature versus nurture, orchestrate a fall from grace for Winthorpe and elevate Valentine to his position, to observe whether Winthorpe turns to crime when stripped of his wealth and whether Valentine will behave as a gentleman when given wealth and power.

As Valentine quickly assimilates into his luxurious new life, learning the ins and outs of commodities trading with surprising aptitude, Winthorpe's life descends into chaos. Framed for theft, drug possession, and soliciting, he finds himself shunned by his former peers and fiancée. Homeless and desperate, Winthorpe meets Ophelia, a kind-hearted prostitute who takes pity on him, helping him navigate his new reality. Meanwhile, the Dukes are pleased with the outcome of their experiment, unaware of the storm brewing as Winthorpe and Valentine's paths begin to intersect in unexpected ways.