The Silver Eagle by Ben Kane
The Forgotten Legion - ten thousand legionaries made captive by the Parthians - has marched to Margiana on the edge of the known world. In its midst are Romulus, Brennus and Tarquinius, all men with good reason to hate Rome. Together the trio must face the savage tribes which constantly threaten the area. But other, more treacherous enemies lurk within the ranks of the Forgotten Legion itself. When all hope is lost, the three friends' character will be tested to the utter limit. Meanwhile in Rome, Fabiola, Romulus' twin sister, also fights to survive. Beset by enemies on all sides, she must travel to Gaul to find her lover, Caesar's right-hand man. There tribal rebellion under the charismatic chieftain Vercingetorix threatens not just Caesar's route to power, but his life and the lives of all who support him.