In 1866 Britain's foremost explorer, Dr David Livingstone, went in search of the answer to an age-old geographical riddle: where was the source of the Nile? Livingstone set out with a large team, on a course that would lead through unmapped, seemingly impenetrable terrain into areas populated by fearsome man-eating tribes. Within weeks his expedition began to fall apart - his entourage deserted him and Livingstone vanished without trace. He would...