Tanzie (HILARY DUFF) and her sister Ava (HAYLIE DUFF) have everything: money, well-dressed hangers-on, and a hot red Mercedes convertible. Though they miss their father (dead two years when the film begins), they are living the fabulous life he made for them as an inventor of natural cosmetics and owner of a hugely successful company that targets 18 to 25-year-old consumers.
When a local Los Angeles TV reporter claims the girls' father repressed evidence of cosmetics that caused skin irritations and diseases, the company is almost instantly devastated. Horrified and unable to deal with being "poor," the girls suffer a series of indignities, most caused by their apparent inability to manage daily tasks. They accidentally burn down their mansion, leave their car with thieves they mistake for valets, and discover that high heels are bad for walking.
They also learn that their trustee and CEO, Tommy (BRENT SPINER), wants to sell out the company to their rival Fabiella (ANJELICA HUSTON). Determined to restore their dad's good name and incidentally, recover their fortune and reputations, they initiate an investigation, based on their viewing of Erin Brockovich. Having been dumped by her TV-soap star fiancé Mic (BRANDON BEEMER), Ava meets and develops a crush on a free clinic lawyer, Henry (LUKAS HAAS). At the same time, because the girls do everything as a pair, Tanzie falls for a Marchetta Cosmetics lab tech, Rick (MARCUS COLOMA), who shares her interest in chemistry.
The sisters' life lessons include generosity and loyalty, as practiced by their longtime maid, Inez (MARIA CONCHITA ALONSO), who invites them to live in her apartment when they lose their home. At last, they find the villain, romances, and corporate success.