Lin Yueyue, the concubine of the Zhenbei Hou Mansion, was treated as a ghost wedding sacrifice by her sister-in-law Su Wan and pushed onto the Xuanbing altar. On the verge of death, her blood accidentally activates the ancient "Xuanling Jade Fetus" under the altar - a secret treasure refined from the blood of the ancient medical sage, carrying the mission of inheriting medical knowledge and balancing the spiritual power of the north. Lin Yueyue fused with the jade fetus and awakened as a "Border Keeper". She gained the magical power of medicine and poison and the spiritual power of herbs, and inherited the secret responsibility of guarding the Northern Territory.
In order to avoid Su Wan and the cold water tribe in the north who covet the baby, Lin Yueyue hid in the "Qinghe Medical Clinic" in the south of the Yangtze River, treating her neighbors with her medical skills, and gradually became famous. In the process, she met Xiao Yi, the king of Yi, who was charged with the "Xuanbing Curse" (a secret technique from the North that was in harmony with the jade fetus). Xiao Yi wants to solve the curse, and Lin Yueyue wants to find the secret of the jade fetus. The two go from suspicion to joining hands.
They uncovered Su Wan's conspiracy to collude with the Cold Water Ministry, and discovered that the Jade Fetus and the Black Ice Curse were originally the bond between the ancient "Medical Guard" and the "Northern Border Guard". In the end, Lin Yueyue used medical skills to resolve the epidemic in the north, and Xiao Yi used military power to put down the rebellion. The two used their "medical heart" and "curse power" to balance, and used the spiritual power of the jade fetus to save the world. Lin Yueyue became a generation of medical saints, Xiao Yi guarded the northern border to ensure people's livelihood, and the desperate situation finally turned into a state of nirvana.
