Beaten and bloodied, down two of their number after the fray in Alexandria, Aemilius and his new comrades of the Hidden Legion make their way back to the Fort, the Legion's mysterious headquarters and seat of power, where they receive new information and a new mission: to infiltrate the mansion of a powerful senator and foil a plot to poison him. A wild chase ensues, from the shores of Greece to the frozen plains of Germania, as the Legion tracks down an enemy who mocks them at every turn...