Captain Iris and Lieutenant Payne, brother officers in the British army, are commanded to report for duty in the Soudan. Hasty preparations are made and the two young soldiers, with their escort, begin their weary march across the hot desert sands. They finally reach an oasis, where a halt is made and the long line of soldiers with their camels and horses are given an opportunity for a brief rest. A quarrel ensues between the two officers and the Lieutenant is struck down suddenly. Through the treachery of their Arab guide the camp is attacked, their horses and camels stolen and the soldiers are massacred by a hundred murderous savages of the desert. Believing the Captain to be the only survivor, the Arabs take him captive to their stronghold in the hills. Years elapse. A caravan is seen slowly winding across the desert. It is part of Kitchener's victorious army passing over the Soudan. A strange creature is seen in the immediate foreground, a snake is crawling along the sands, the being raises his cudgel and is about to kill the snake when he espies the caravan coming towards him and immediately bounds away in fright. He is pursued by the soldiers, who bring him to bay in his cave on the hillside. After a desperate fight the soldiers bring him out into the sunlight and find that he is a white man, one of their own race, but stark, raving mad. Hanging to the tattered rags upon his back is a button of the British army. Was this poor, wild, raving creature once a British officer? The flag is fetched and placed before him. He sees it and pauses in his wild fear. Wildly he clutches the banner. The soldiers stand in breathless expectancy. Slowly he looks from one to the other. Something from the hazy past comes to him. Gradually he remembers; he was once one of them. The soldiers at last reach their home post. The desert has been robbed of its prey. The lost comrade has been brought back to life and love and civilization. But who is he? The denouement is happy and startling and brings to a finish one of the best pictures ever made by Selig.