In 1875 Captain Matthew Webb, a retired merchant seaman, survived fierce winds, treacherous currents and multiple jellyfish stings to swim from Dover to the shores of France, a crossing that took almost 22 hours and spanned 39 miles. The Channel would not be swum again for 36 years, and to this day more people have climbed Everest than successfully swum across the Channel. The Greatest Englishman tells the story of one man's struggle to define himself, beginning with Captain Webb diving into the water at Dover.