The year is 53 BC. The disastrous Battle of Carrhae is over. Forty thousand Romans lie dead on the field. Tribune Marcus Drusus Pontus must negotiate to save his men's lives. He and they must serve the triumphant Parthians, or die. They will be marched far to the east, over the plains and the mountains, to a strange land with stranger people, to guard the frontier and patrol the road that leads to the land of silk. With them will go a Parthian interpreter, a boy named Ardavan whose mother was a Roman, and who soon finds that Rome looks after her own. And then the Parthian Emperor changes his mind ...