In ancient times, the Human Emperor, Zhao Ming, petitioned on behalf of the people and sacrificed himself to resist the divine realm. After Zhao Ming's fall, his beloved, Hun Dunzhu, risked her life to save a wisp of his soul, setting up the cycle of reincarnation for eternity. In the distant future, Zhao Ming reincarnated as Xie Xuechen, the leader of the Immortal Alliance, while Hun Dunzhu became the Holy Maiden Mu Xuanling in the Dark Domain. The two finally reunited in the mortal realm but had forgotten their past, becoming adversaries in a "righteous versus evil" struggle. Mu Xuanling saved the heavily injured Xie Xuechen in the Dark Domain and coerced him to travel together in gratitude for saving his life.

上古时期，人皇昭明为万民请命，牺牲自己对抗神界。昭明陨落后，爱人混沌珠拼死救下他的一缕魂魄，布下万世轮回之局。万世之后，昭明转世成仙盟盟主谢雪臣，混沌珠亦成为暗域圣女暮悬铃。两人终于在人间重逢，却已经忘却前尘，变成“正邪不两立”的对手。暮悬铃在暗域救下重伤的谢雪臣，以救命之恩要挟与他同行。一路上，两人从各怀心机到并肩作战，卸下防备的同时暗生情愫。然而，在争夺神器“混沌珠”的阴谋中，两人陷入生死考验。暮悬铃因救世牺牲，谢雪臣逆天改命，回到过去救出暮悬铃。万世之劫结束，谢雪臣终于魂归昭明，昭明本体却已沦为堕神。暮悬铃用爱唤醒堕神，消弭浩劫，天下太平。