AD 117. The Roman Empire stretches from Egypt to Spain, and east as far as the Black Sea. But in northern Britain, the relentless onslaught of conquest has ground to a halt in the face of the guerrilla tactics of an elusive enemy, the savage and terrifying Picts, led by revenge-hungry warrior Etain. When the Roman legion is ambushed, the seven surviving Romans pledge to rescue their leader and return to Rome to regroup.