The plot is set in 1884, Sudan, beginning shortly before the fall of Khartoum at the hands of the Mahdi. British trader and businessman Ryder Courtney, the younger brother of Waite Courtney, arrives in Khartoum to sell his wares, only to have them commandeered by General Charles George Gordon. General Gordon later has Ryder evacuate citizens from the besieged city on his river steamer, the "Intrepid Ibis", but the steamer is attacked and damaged by the Mahdists as it tries to escape, stranding Ryder in Khartoum.