377 AD: When Optio Numerius Vitellius Pavo and a select group of the XI Claudia are summoned to the Persian front, they leave Thracia behind, knowing little of what awaits them. They know only that they are to march into a burning land of strange gods. They whisper tales of the mighty Persian Savaran cavalry and pray to Mithras they will see their homes and families again. All too soon it becomes clear to them that this is no ordinary mission - indeed, the very fate of the empire might rest upon their efforts. But for Pavo the burden is weightier still, for he knows that the east also holds something even more precious to him . . . the truth about his father.