Back then, I thought you were my beloved. Qing'er, a 500-year-old snake demon, faces a calamity that will leave her dead within six months and unable to enter the cycle of reincarnation. Following her immortal master's orders, she descends the mountain to take Zhao Jin, the deposed crown prince, as her disciple. She believes her obedient and seemingly frail apprentice is merely a pitiful soul in need of protection. Little does she know that Zhao Jin is calculating, sinister, and ruthless, having lain in wait for years with one goal: to reclaim the imperial throne.