It is 313 AD, and tempers are rising in Rome. The Emperor Constantine and his mother Helena are trying to make sense of the new Christian religion which is spreading through the Empire. Scholars are locked in a bitter struggle over whether Christ really was the son of God, and Constantine invites delegates from both sides to debate before him at his villa. Soon after the meeting, envoys from both sides are found murdered in a most macabre fashion, and the Holy Sword is later discovered to be stolen. Helena calls on the help of her secret agent Claudia—a shrewd, unobtrusive detective—to untangle the dangerous web of intrigue.