Britain, the 6th century: Artorious Castus (Owen), better known among his people as Arthur, is the leader of a select group of Sarmatian knights who, after impressing the occupying Roman forces with their fighting skills and righteous honour, have been incorporated into the elite ranks of the Roman army.

However, the occupying forces are withdrawing from Britain to protect Rome from the onslaught of barbarians on the continent and with freedom on the horizon after 15 years of bloody service, Arthur and his knights must protect the liberty of the country from invading Saxons...