In 1929, at the Golden Jubilee of Light banquet celebrating the fiftieth anniversay of the invention of the electric lamp, Thomas Edison, the guest of honor, reflects as the toastmaster recalls his achievements: Arriving in New York as an unknown inventor, Edison tries to interest Taggart, the manager of a firm that supplies gold quotes to the board of trade, in his ideas about electricity. The shortsighted Taggart ignores the young inventor until the ticker machine breaks down and Edison repairs it. Impressed by Edison's ingenuity, General Powell, the president of Western Union, offers him a job at the Western Union workshop. There Edison is befriended by Mary Stilwell, a secretary at the company. Assisted by fellow workers Bigelow, Lundstrum and Michael Simon, Edison perfects the stock ticker and sells it to General Powell and Taggart. With the proceeds, Edison opens his own laboratory in Menlo Park, New Jersey and weds Mary. As time passes, Edison finds himself on the verge of insolvency and is about to lose his company when his friend Powell dies and he is forced to turn to Taggart for help. When Taggart insists upon total control, Edison refuses his offer and is near bankruptcy. In the nick of time, Edison invents the phonograph, which saves his lab, but he is beset by more problems when his friend, Bunt Cavatt, tells the press that he has developed an electric light. Branded as a charlatan by the scientific community, Edison strives to perfect his light invention. Enduring years of failure, Edison perseveres until he discovers incandescent light. Opposed by the gas interests led by Taggart, Edison is granted six months to prove that he can light New York City. At the last minute, Edison throws the switch to his generators and miraculously illuminates the city.