Four female friends and former classmates – Xia Yan, Zhao Xiaolei, Xiang Nan, and Han Shuang – have formed a bond that could last a lifetime. But as they approach the end of their twenties, they all find themselves facing up to a range of very different challenges.

On the Earth, a catastrophe triggered the variation of all kinds of species. The superior survived and the inferior were extinct. Under this circumstance, Luo Feng inherited from the owner of Yunmo Star and became one of the three strongest people on the Earth. He lost his flesh during the fight against giant swallowed monster but then he took the flesh of the monster. In the flesh, he developed a human body. Later, he stepped out of the Earth and headed to the universe.

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.

天才医生郑仁（张彬彬 饰）因要查探十八年前“冤案”的真相来到海城医院，与急诊科“咸鱼”主任苏云（代旭 饰）组成了一对“欢喜冤家”，在相互扶持间攻克了一个又一个疑难病症，开启了一段“爽、燃、酷、嗨”的医学之旅。在此期间，郑仁不仅揭开了当年事件的“残酷真相”，也同时与苏云、林渊、谢伊人等人组成了“连体分离术”攻坚小组，秉持着自己心中那一份白衣天使的初心，在反复的模拟训练和坚定不移的医学精神指引下，实现了拯救生命、治愈病患、温暖人心的医生理想。