In ancient Rome, Marcellus Gallio, a military tribune, is assigned to oversee the crucifixion of Jesus Christ. Marcellus wins Jesus's robe in a gamble, but soon after, he experiences troubling visions and overwhelming guilt. Haunted by these feelings, he embarks on a journey to learn more about the man he put to death, seeking solace and answers. His path crosses with several believers, including Peter, who gradually expose him to the teachings and miracles of Jesus, shaking the foundations of his beliefs and allegiance to Rome.

As Marcellus grapples with his internal turmoil, he is drawn into a conflict between his duty as a Roman officer and the burgeoning Christian faith growing within him. The robe becomes a symbol of his struggles, a constant reminder of his actions and a source of mystical influence. Alongside his romantic interest, Diana, Marcellus faces increasing danger from Roman authorities as he explores this new faith. His journey of redemption and spiritual discovery takes unexpected turns, challenging his loyalty, courage, and understanding of truth and justice.