The Roman legions are being withdrawn from Britannia to fight in the Dacian wars and the Caledonii revolt. The only barrier to a complete invasion of Britannia is a handful of auxiliary units. Marcus' Horse have to fight treachery, witchcraft, spies and murder. They have to battle the elements and a ferocious foe who outnumbers them in every battle. When their iconic leader is accused of treason Britannia looks like a bleak place for Marcus' Horse.