Albert Einstein's revolutionary theory that turned the world upside down might have been dismissed but for a math mistake, a cloudy sky, and the start of World War I. This fascinating two-hour special tells the story of Einstein's little-known, 15-year struggle to prove one of his most radical theories -- a theory that upended Newton and three centuries of scientific thought and called into question the definitions of space and light and gravity -- the game-changing concept known as the Theory of General Relativity. Today, more than a century since the "Miracle Year" in which he published many of his breakthrough papers, Einstein's ideas remain a living, vibrant influence. They continue to push scientists farther, and deeper, into the universe than even he could have imagined.