On the morning of June 8, 1924, George Mallory and Andrew Irvine started up the final slopes of Mt. Everest with a good chance of being the first ever to climb the world's tallest mountain. Shortly after midday, they were spotted less than 1,000 feet away from the top. Then clouds rolled in and they were never seen again. This special program examines their legendary effort and the enduring mystery of whether they made it to the top.