In a small town, a young boy is bitten by a mysterious snake, bringing him to the brink of death. The local doctors believe his condition is incurable, with the poison having reached his heart. Despite facing imminent demise, the boy's concern lies not with himself but with his mother's future and filial responsibilities.

In this critical moment, a hazy voice whispers in his mind, offering to help him fulfill his unfinished wish. Thus awakens the Immortal Medical Saint within his body, only to find himself in a different world known as Earth. Here, the path of immortality has declined, technology thrives, and spiritual energy is scarce. However, he discovers that his remarkable talents, tragically destroyed or taken away in his previous life, now reside within his new vessel.

Struggling to comprehend his new reality, he unexpectedly enters a marriage with Soong Xixue, who agrees to the arrangement as a business deal. As they settle into their new life together, he gradually uncovers more about her and their intertwined destinies.

His journey in this unfamiliar world becomes intertwined with countless dangers, secrets, and hidden powers waiting to be unearthed. Armed with his knowledge of medicine from his past life as a Medical Saint, he embarks on an adventure where he must balance his extraordinary abilities with his newfound mortal existence. All of this is driven by his unwavering pursuit of a greater goal.

C400 The Sky Guard