Lion of the sun

the long version

"AD 260 - Mesopotamia. Betrayed by his most trusted adviser, the Roman Emperor Valerian has been captured by the Sassanid barbarians. The shame of the vanquished beats down mercilessly like the white sun, as the frail old Emperor prostrates himself before Sharpur, King of Kings. Ballista looks on helplessly, but vows under his breath to avenge those who have brought the Empire to the brink of destruction with their treachery ... But first he must decide what price he will pay for his own freedom. Only the fearless and only those whom the gods will spare from hell can now save the Empire from a catastrophic ending."--Publisher description.