Gu Yao transmigrates straight into hell: as a sacrificial offering of the Gu Clan, she is presented to a pig demon. The original host was exposed to every kind of poison from childhood, while her master used humans as vessels to cultivate Gu. Gu Yao strikes back, kills her master, refines Gu, and slays the pig demon, unlocking the 'Slay Demons to Transform into Gu' system. To protect her sisters, she joins the Demon-Suppression Bureau. Starting as an ostracized remnant of an evil cultivator faction, she fights her way up to become a First-Rank Governor. Every time she kills a demon, fragments of memory reveal the same white-haired woman: the Gu Ancestor, whose face is identical to hers. After traveling across the Four Regions and gathering all five branches of Gu techniques, she finally discovers that the Gu Ancestor did not disappear all those years ago but was hunted down by the royal court. Gu Yao returns to the capital, overturns the imperial throne, and becomes emperor. But a new crisis is only just beginning.