A living pilgrim is led by a classical Roman poet from a dark sea-shore to the slopes of a sacred mountain where souls undergo moral purification. The journey ascends through ordered terraces that each correct a particular vice, populated by penitent souls, symbolic punishments, and instructive dialogues that illustrate themes of repentance, divine justice, and rightful love. Cantos alternate scene, witness, and theological reflection, moving from shadow toward increasing light. The pilgrimage culminates at an earthly paradise on the summit where a heavenly woman appears to succeed the human guide and the traveler prepares for the next stage of ascent into the celestial realms.