The bodies of three men and two children have been found entombed in a cave in one of the most inhospitable places on earth, the edge of Bolivia 's vast salt plain - the Salar de Uyuni. James and Tiffiny discover that at least three of the skeletons show signs of blows to the head powerful enough to kill them. Is this a case of piracy on the salt plain? Human sacrifice? Or possibly even both? In Part 2: London 's Greenwich Naval Hospital , used from 1750 to 1840 for retired sailors, was the resting place of some 20,000 souls - vital skeleton clues to life in the Georgian Navy. John and James examine a skeleton to unlock the story of one dead sailor: a black male with an amputated leg. On board HMS Victory, they explore how he might have sustained his injuries and how an amputation before the age of anesthesia would have been performed on board a ship.