It is AD 55. As trouble brews on the eastern fringes of the Roman Empire, Tribune Cato and Centurion Macro must prepare for war...

The wily Parthian Empire has invaded Armenia, a frontier territory claimed by Rome, ousting King Rhadamistus. The king is ambitious and ruthless, but he is vital to Rome's strategic interests. General Corbulo must restore him to power, while also readying the troops for war with the powerful Parthian Empire. Corbulo orders new arrivals Cato and Macro, and their elite cohort of Praetorian Guards, to carry out the task.

Marching into unmapped and unfamiliar terrain to restore an unpopular king is a perilous mission. Allies cannot be trusted and foes lurk on all sides. The bravery and skill of the Roman army will be tested to the limit . . .