Tullius Valerius -- a Proconsul of Rome, circa 310 A.D. -- fears that a provincial governor named Gaius Appius Quintillianus has been secretly working with those Germanic barbarians seeking to end Roman rule. Valerius elevates Marcus, a gladiator turned soldier, to the post of Vice Proconsul with orders to go "undercover" to investigate this situation. Marcus selects two friends, fellow soldier Claudius and pickpocket Volcan, to accompany him into Gaius' territory. In this territory lives Lycia, daughter of Manlius and the beloved of Marcus. Gaius soon learns of Marcus's plans, thanks to the evil Stovius. Gaius kills Manlius and blames the crime on Marcus. Lycia turns against Marcus whom Gaius condemns to be pulled apart by teams of horses. Marcus survives this "Test of Strength" as reinforcements arrive from Rome. Gaius dies in battle, Claudius reunites with his Christian girlfriend, Diana, and an enlightened Lycia welcomes Marcus back with open arms.