Centuries before Hell's assaults on Mars and Earth, the Night Sentinels of Argent D'Nur stand alongside their celestial partners, the Maykrs, in a brutal struggle against demonic hordes intent on seizing a legendary relic called the Heart of Argent. The Maykrs deploy the Doom Slayer as their ultimate weapon, augmenting him with divine power—yet they bind him through the Tether, a device that strips away his autonomy and reduces him to nothing more than a tool of their will. When the demon commander Prince Ahzrak abandons direct confrontation in favor of hunting the Heart itself, the war's momentum shifts dangerously, and cracks begin to splinter the alliance between the Sentinels and their supposed saviors. Buried under layers of control and deception, the Slayer must find the strength to sever his chains and forge his own path, becoming a threat not just to the infernal forces but to those who claimed to stand with him all along.