On January 28, 1914, the liner Prinz Heinrich inexplicably lost one of its passengers. James Regan and all of his luggage vanished midvoyage between Marseilles and Naples. The ship was full, but no one saw him go overboard. In 1848, in Australia, explorer Ludwig Leichhardt attempted a second expedition across the country's daunting central desert. All of the men and the expedition's seventy pack animals completely vanished. Over 125 years later, photos of aboriginal cave paintings depicting Leichhardt's expedition came to the attention of Australian ranger Zac Mathias. Mathias arranged for an expedition of his own to find the cave paintings, but just before they set out, Mathias himself completely disappeared.