On the border of the Yan Dynasty, at Longmen Pass, known as the "desperate situation", an unprecedented disaster quietly came. A strange plague called "Black Scale Disease" spreads in the city. The infected people will quickly lose their minds, develop hard black scales on their skin, and turn into "Black Scale Demons" who only know how to kill. Longmen Pass Commander-in-Chief Long Xiang, a pure warrior who believed in iron and blood, led his soldiers in a bloody battle, but found that conventional weapons could not withstand the tide of monsters. Just when the whole city was on the verge of collapse, Gu Yunzhou, a genius disciple of "Tianji Pavilion" who was ordered by his master to investigate the source of the demonic energy, arrived. Long Xiang's military strategy and Gu Yunzhou's Xuanmen magic, two completely different power systems were forced to combine in a desperate situation. From initial suspicion and collision to gradual trust, they join forces to fight against the ever-evolving Black Scale Demon, and step by step trace the source of the disaster - a mysterious sect that attempts to use all the creatures in the city as sacrifices and perform evil rituals. This is a city-defending epic written by mortal martial arts and mysterious Taoism. It is also a journey of growth for two protagonists with very different personalities to understand their responsibilities and achieve self-transcendence.
