Brantley Foster (Michael J. Fox) is a young college graduate who has just earned a degree in business in his home state of Kansas. He travels to New York City to join a large investment firm in an entry-level position he obtained while still a student. He moves into a crummy Manhattan studio apartment and prepares for work.When he arrives at the firm, he finds that it's closing because it was acquired in a hostile takeover and that 90% of the workforce, including himself, is now jobless. However, even without employment, Brantley refuses to give up looking for another job. He's repeatedly turned down with all his interviewers telling him that he lacks the experience necessary.With no good prospects, Brantley decides to play his last card: prior to leaving Kansas, his mother tells him that he's related to Howard Prescott (Richard Jordan), a distant uncle & the CEO of Pemrose, a large New York investment firm and one of the richest in the world. Brantley goes to his uncle's office and convinces Prescott's secretary to give him five minutes alone with Prescott himself. Prescott and his secretary seemed very impressed with Brantley's tenacity (the young man creates a business card by photocopying his smiling face and signing it) and Prescott gives him a job working in the Pemrose mail room. Brantley is immediately disliked by his boss and teamed up with another worker, Fred Melrose (John Pankow), who teaches Brantley how to deliver the mail and leave enough time for goofing off. Fred also tells Brantley not to mix with the executives in the building while he makes deliveries. Brantley is also able to acquire information about the company by looking through memos and other important documents, gaining as much knowledge as he can about the inner workings of the corporation.Back in the mail room, Brantley is charged with driving another Pemrose exec, the bad-tempered Vera (Margaret Whitton), to her home in Litchfield in a limo after her car broke down. His boyish charm soon wins her over on the ride and she invites him to stay for a drink at her palatial estate. She tells him about how her marriage has faltered and that she feels unattractive at her age. Brantley is able to convince her otherwise and the two take a swim where she seduces him. After having sex, she tells him she'll help him advance in the company. Brantley tells her he wants to make it on his own. Just then Vera's husband comes home. Brantley is terrified to know he's coming toward the pool house and is even more terrified to see that it's Howard Prescott himself. Babbling about how he's disgraced his family by having sex with his aunt, he bolts out and leaves.During their mail rounds, Fred informs Brantley that an exec had been fired and that the mail room staff knew about it three days ahead of the man getting the news. Brantley sits in the office dreaming about being an exec when the phone rings. One of the man's contacts has called asking why there are shipping problems for his company in the Midwest. Brantley is able to set up a shipping plan for the company, his initiative in solving the problem impressing the rep. The next day Brantley goes to the same office before his mail rounds and is able to procure a secretary for himself and set himself up in the terminated exec's place, adopting the alias Carlton Whitfield. Though he's very careful to hide his intentions, his boss in the mail room begins to suspect him.Brantley attends a meeting of the high-level Pemrose management and meets Christy Wells (Helen Slater), an attractive exec whom Brantley is immediately smitten with. She's initially quite rude and dismissive but eventually warms to him. At the meeting, it's announced that another powerful CEO, named Donald Davenport (Fred Gwynne), is acquiring large portions of Pemrose stock in a bid to take over the company. Prescott's aide tells them that they have to look for budget items to slash to build a fund to protect the company. Brantley dissents, saying that rapid and aggressive expansion is a better plan that will make the company's stock too valuable for Davenport to commit a hostile takeover. His idea is squashed with Prescott's aide telling him he's too young to be taken seriously.Meanwhile, Christy has been involved in an affair with Prescott himself. He asks her to spy on Brantley and she steals a folder of his work from his office. One night while he's working late, Christy stops by his office and sees the results of his research. The two have a late night conversation about the best plan of action to prevent Davenport's hostile takeover. Though they disagree on almost everything, Christy starts to realize that Brantley's plan of expansion is the best way to save Pemrose. The two spend the entire night together, talking and finally have sex.The next day, Prescott himself announces that he'll hold a retreat at his Litchfield home for all the top-level execs so they can work out a plan. Brantley had initially planned not to attend but is invited by both Vera and Howard. Howard believes Whitfield is a spy sent by Davenport to gain further inside information, while Vera wants Brantley there to meet Pemrose's top investors, thinking his boyish charm will win them over -- her assumption is correct and Brantley spends several hours talking to them and convincing them of his new ideas in the arena of business. Howard also tells Brantley to keep Vera occupied during the retreat, then charges him with keeping Christy away from Whitfield.At night, everyone sleeps in separate rooms. Howard sneaks out of his room looking for Christy, who'd put an end to their affair earlier that day. Brantley also sneaks out looking for Christy in her room. Vera sneaks out looking for Brantley. They all eventually converge on Christy's room, with Brantley hiding in the bed, Howard believing him to be Christy and Christy and Vera suddenly finding them both together. Brantley had also found his stolen files in Christy's room. Howard and Christy finally now know that Whitfield is actually Brantley. Vera is now aware of Howard's affair with Christy and she decides to divorce Howard. Brantley confronts Christy about stealing his files and storms out leaving her alone and dejected.Back at Pemrose, Brantley and Christy are both fired. After arguing about infidelity, they have sex in the elevator and return to Brantley's office to figure out a new plan for Pemrose, engaging the help of Fred and Brantley's secretary, Jean. At a meeting of Prescott's management execs, Donald Davenport arrives where he icily assures Prescott that most of his high-level staff will keep their jobs. Brantley and Christy walk into the meeting and announce that Pemrose will not be bought out by Davenport because Brantley was able to gain the support of the investors from the retreat. Instead, a merger will occur between Pemrose and Davenport's corporation. He also announces that such a merger wouldn't be possible without the support of Pemrose's biggest stockholder, Vera, who'd gained control of more than half the company's stock. As the new owner, Vera confronts her husband directly and tells him that he's fired and has security escort him and his aide out of the building.That night, the new owners of Pemrose go to the Metropolitan Opera to celebrate. The limo they ride in is driven by Brantley's mail room boss. Vera's date is Fred and Brantley and Christy begin a new relationship together.