Once every fifty thousand years, upheaval in the Guixu tears open its seal, and the ancient divine beast Xuanwu seizes the chance to escape. Disguised as Xuan Qing, a roasted sweet potato vendor, he hides amid the bustling streets of Yongning, the capital of the Great Zhou. He only wants to lie low and evade the Guixu pursuers, but while tending his stall, he unexpectedly saves the Second Prince, Zhou Jingyan, whose horse has run out of control. He also discovers a strange Guixu mark on the dissolute prince. Bai Li, a fox immortal from Tushan, has been ordered to investigate strange happenings in the city and soon realizes that Xuan Qing is no ordinary person. The two strike a deal: Bai Li will help conceal Xuan Qing’s aura, while Xuan Qing investigates the secrets surrounding the prince. As they dig deeper, they discover that Zhou Jingyan has been led astray by the Imperial Preceptor, Xuchenzi, and branded with the Guixu’s master seal. Beneath Yongning lies a fragment of a vast “Guixu Summoning” array, and the city’s people have already been tainted, without their knowledge, by the lingering effects of its mark. Xuchenzi has secretly seized local deities and turned them into the array’s cores, hoping to fully activate it on the night of the full moon and transform Yongning into an earthly projection of the Guixu. Xuan Qing and Bai Li form an alliance, facing a steady stream of Guixu pursuers while wrestling with the divine and demonic forces within themselves. They resolve to stop the catastrophe. As the mark’s corruption leaves Zhou Jingyan drifting in and out of consciousness, the goodness still left in him becomes their greatest hope of breaking the deadlock. The glow of street-side cooking fires illuminates the hidden currents swirling through the three realms, while the sweet scent of roasted sweet potatoes mingles with sinister schemes. A turbulent journey revolving around the mystery of the Guixu, and drawing the realms of humans, immortals, and demons into its wake, quietly begins in the bustling lanes of this prosperous ancient capital.
