The Tungrians have no sooner returned to Rome than they find themselves tasked with a very different mission to their desperate exploits in Parthia. Ordered to cross the river Rhenus into barbarian Germany and capture a tribal priestess who may be the most dangerous person on the empire's northern border, they are soon subject to the machinations of an old enemy who will stop at nothing to sabotage their plans before they have even set foot on the river's eastern bank. But after their Roman enemy is neutralised they face a challenge greater still.