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 Paradigm shift 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 bitter and 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.