One of the most exciting periods of Britain's history under the Romans remains largely unknown today. Yet, at the end of third century AD, two men successively ruled the island, together with parts of the Continental coast, as emperors of Britannia for a period of ten years. They minted their own coins, initiated Britain's first truly integrated defence system and successfully repelled an invasion from the mighty Roman empire. This is the story of Carausius and Allectus - the rebel emperors of Britannia.