The Gate of Time

Roger Two Hawks, an American Indian, was shot down over Ploesti, Roumania near the end of World War II; only the Navigator, O'Brien, survived with him. Then, strangely, they were in a foreign land, where no known 20th Century language was spoken, where the people seemed to be living in another time, where men carried bows and arrows. Then the realization struck: somehow they had entered a parallel universe, through a temporarily opened gate in the atmosphere. Somehow, they must get out; and then O'Brien was dead.Now, would the nightmare begin.or what?