The world is plunged into the “Gray Fog Crisis.” An unknown virus turns humanity into mindless “walking corpses,” and the survivors must scavenge for supplies in the ruins while fighting off mutants. The protagonist, Lin Mo, unexpectedly awakens the ability to “turn back time.” Every time he dies, he returns to thirteen hours before the disaster began. But he discovers that each time the world resets, subtle changes appear, while his own memories are gradually being eroded.