In the 1990s he covered Ethiopia, Somalia, Rwanda and the Congo for Reuters. Three of his colleagues were killed by a mob in Somolia during a rebellion against the presence of U.S. forces, and he witnessed the atrocities in Rwanda. Hartley grew up in Africa, the son of a British colonial officer. After the death of his father, Hartley found in a chest his father had given him the diaries of his father's best friend who had died mysteriously 50 years earlier. Hartley set out to find out what happened.