Hellbound takes place in 2022–27 in South Korea. An otherworldly face called an angel suddenly starts to materialize to deliver prophecies called decrees that condemn certain individuals to Hell at a specific future time, either seconds or years away. Three monstrous supernatural beings called demons appear at almost the exact time to maul and incinerate the person's body in a spectacular show of force called a demonstration. Two organizations in cahoots, the cult-like New Truth Society and the gang-like Arrowhead group, gain power by playing on people's fears.

In a chaotic world exacerbated by the continuous hellbound decrees, lawyer Min Hye Jin of Sodo, The New Truth Society, and the Arrowheads get entangled anew amidst the sudden resurrections of the formerly condemned; The New Truth’s Chairman Jung Jin Su, and Park Jung Ja.