Nikola Tesla today is largely unknown and overlooked among the great scientists of the modern era. While Thomas Edison, the most famous inventor in American history, gets all the glory for discovering the light bulb. But it was his one-time assistant and life-long arch nemesis, Tesla, who made the breakthrough in alternating current electricity.

Edison and Tesla carried on a bitter feud for years, but it was Tesla's AC generators that illuminated the 1893 World's Fair in Chicago under artificial light. Today all homes and electrical appliances run on Tesla's AC current.

120 years ago, they were billed as the 'Twin Wizards of Electricity', here Nigel Cawthorne chronicles the life and times of the two great men to help us finally decide just who really is the Electric King- Edison or Tesla?