The Secret of My Success (1987)

Recent college graduate Brantley Foster (Michael J. Fox) travels from his home in Kansas to New York City to pursue a new finance job. However, when Brantley arrives, he learns that his position has been eliminated, and he's forced to take a job working for his inept Uncle Howard (Richard Jordan), who became a company president through marriage. Brantley starts as a mere mailroom worker, but quickly climbs the corporate ladder when he begins posing as an executive.