Part of the documentary series looking at real-life stories of courage and self-sacrifice. 'Did They Exist?' looks at the searches undertaken by numerous explorers to find the lost cities of ancient antiquity, including Hiram Bingham's discovery of Machu Picchu in 1911, and the discovery of the lost city of Ur by Sir Leonard Wooley in the 1920s. 'The Race to the Moon?' examines the development of rocket technology by the Nazis during the Second World War, and the uses the Americans made of this technology to help get them to the moon in 1969. Finally, 'Amazon Adventures' looks at the first attempts to trace the source of the mighty Amazon river, including the mysterious disappearance of Colonel Fawcett in 1923.