Xiao Yan awakens the discarded martial spirit Black Water Serpent, only to be jilted by his fiancée and humiliated by his sect. He forges a blood pact to coexist with the serpent, evolving endlessly through devouring. He meets a Wine Sword Immortal, tames an ugly bird, braves deadly lands, and battles rival sects. Gravely wounded, he transcends through nirvana, storming the hypocritical Immortal Realm and uncovering its secret of refining poisonous Gu insects. In the end, he sacrifices himself to merge with the serpent and ascend to the rank of Sovereign Lord. He slays the Immortal Sovereign, shatters the realm barrier, and reshapes a rule of equality for all living beings. Transforming into a stellar gatekeeper, his legend endures for eternity.