In 1981, San Francisco salesman Chris Gardner invests his entire life savings in portable bone density scanners, which he demonstrates to doctors and pitches as a handy quantum leap over standard X-rays. The scanners play a vital role in his life. While he is able to sell most of them, the time lag between the sales and his growing financial demands enrage his already alienated wife Linda, who works as a hotel maid. The financial instability increasingly erodes their marriage, in spite of them caring for Christopher Jr., their soon-to-be five-year-old son. Because Chris has trouble selling the scanners, as they only produce a slightly better picture than a common X-ray but for a much higher price, and hence does not make enough money to make ends meet, Linda has to work double shifts.
While Gardner is trying to sell one of the scanners, he meets Jay Twistle, a manager for Dean Witter Reynolds, and impresses him by solving a Rubik’s Cube during a taxi ride. After Jay leaves, Gardner lacks money to pay the fare and chooses to run instead, causing the driver to angrily chase him into a BART station. Gardner boards a train but loses one of his scanners in the process. His new relationship with Jay earns him the chance to become an intern stockbroker. The day before the interview, Gardner grudgingly agrees to paint his apartment so as to postpone being evicted due to his difficulty in paying the rent. While painting, Gardner is greeted by two policemen at his doorstep, who take him to the station, stating he has to pay for the numerous parking tickets he has accumulated. As part of the sanction, Gardner is ordered to spend the night in jail instead, complicating his schedule for the interview the next morning. He manages to arrive at Dean Witter’s office on time, albeit still in his shabby clothes, wearing his undershirt, a gray jacket and jeans, with paint splashes all over his clothes and face. Despite his appearance, he impresses the interviewers and lands an unpaid internship. He would be among 20 interns competing for a paid position as a stockbroker.
Gardner’s unpaid internship does not please Linda, who eventually leaves for New York because she might get a job at her sister’s boyfriend’s new restaurant. After Gardner bluntly says she is incapable of being a single mom, she agrees that Christopher Jr. will remain with his dad. Gardner is further set back when his bank account is garnished by the IRS for unpaid income taxes, and he and Christopher are evicted. He ends up with only $21.33, resulting in them being homeless, and they are forced at one point to stay in a restroom at a BART station overnight. Other days, he and Christopher spend nights at a homeless shelter, in BART, or, if he manages to procure sufficient cash, at a hotel. Later, Gardner finds the bone scanner that he lost in the BART station earlier and, after repairing it, sells it to a physician, thus completing the sales of all his scanners.
Disadvantaged by his limited work hours, and knowing that maximizing his client contacts and profits is the only way to earn the broker position, Gardner develops a number of ways to make phone sales calls more efficiently, including reaching out to potential high-value customers, defying protocol. One sympathetic prospect who is a top-level pension fund manager even takes Chris and Christopher to a San Francisco 49ers game at Candlestick Park. Regardless of his challenges, he never reveals his lowly circumstances to his colleagues, even going so far as to lend one of his bosses $5 for cab fare, a sum that he cannot afford. Concluding his six-month-internship, Gardner is called into a meeting with his managers. To break the ice, Gardner jokes that he is wearing a shirt (unlike the undershirt he wore during his interview) as it is his last day and thought to dress for the occasion. The manager Martin Frohm smiles and says he should wear another one tomorrow as it will be his first day, letting him know that he has won the coveted full-time position and giving him back his $5 as he promised. Fighting back tears, Gardner shakes hands with them, then rushes to his son’s daycare to embrace Christopher. They walk down the street, joking with each other (and are passed by the real Chris Gardner, in a business suit). The epilogue reveals that Gardner went on to form his own multimillion-dollar brokerage firm.