Jane Quimby and her brother, Ben, are going through a financial rough patch. When she sees an ad for a paid internship at a fashion house, she decides to apply and enroll in her school's work study program. But in a paperwork shuffle, the HR rep mistakes Jane for an older, more qualified Jane… and our Jane suddenly finds herself with a part-time job as the executive assistant to a very demanding Gray Chandler Murray!
Her best friend Billy agrees to help her forge some documents that will allow Jane to work as an adult. This new income will help with her family debt. As compensation, Billy demands that Jane comes with him to a house party where he meets up with his secret girlfriend, Lulu, Jane's high-school nemesis.
Back at Donovan Decker, the hip fashion house Jane is working at, part of Jane's demanding new schedule is to spy on Gray's ambitious underling, India, who is out for Gray's job. Jane is able to thwart India's plan to discredit Gray by showing a taste of her department's new merchandise in an important meeting. Jane manages to save the day - and her new job.