It is 69 AD and the year of four Emperors. The Empire is in turmoil and, on the Northern Frontier, a loyal ally of Rome, Queen Cartimandua is fleeing fo her life. Fate thows her in the way of a Roman Decurion, Ulpius Felix who rescues her and her mythical sword. Treachery at home and the power of the Druids conspire to drive Rome from its precarious foothold in Britannia. When the Queen is murdered the whole of the frontier threatens to erupt in revolt. It takes Ulpius Felix and his auxiliary cavalry to save Rome and save Britannia.