In a Roman Empire in full expansion, a young tribune named Marcellus Gallio, known for his carefree life and fearsome ambition, finds himself trapped in an internal conflict after a series of transformative events. After being assigned to carry out the crucifixion of a prisoner named Jesus Christ, Marcellus is deeply affected by the sacrifice and dignity of the condemned man. As part of his reward, he receives a tunic, which Jesus wore at the time of his death.
As Marcellus wears it, he begins to experience mysterious visions and unsettling dreams that lead him to question his faith and his place in the world. Upon his return to Rome, he tries to erase the mark of his past, but the powerful influence of the mantle continues to haunt him. His life becomes even more complicated when he falls in love with a young Christian woman named Diana, who shows him a new perspective on suffering, redemption, and love.
Meanwhile, the rest of his life is under the threat of the emperor, who sees Christianity as a threat to his power. As Marcellus gets embroiled in the struggle between good and evil, and between the empire and faith, he must confront his own demons and find true redemption. The internal struggle of this tribune will lead him on an unexpected journey toward spirituality and truth, redefining what sacrifice and eternal love truly mean.