Jiang Yun is a frail five-year-old boy born into the wealthy Jiang family, though his position is precarious due to his father's rebellious marriage into the Qinglong Gang, a powerful underground organization. On his birthday, his parents die in a plane crash, leaving him an orphan. While suffering from a severe fever at the hospital, Jiang Yun binds with a supernatural entity known as System 7777, or Xiao Qi. The system reveals that Jiang Yun is destined to live a short life unless he completes specific tasks. His mission is to save his uncle, Du Mengxi, who is the ruthless leader of the Qinglong Gang and the novel's antagonist. The system explains that in the original timeline, Du Mengxi is eventually killed by an undercover police officer, leading to the collapse of the world's energy. Jiang Yun must prevent this tragedy by guiding Du Mengxi away from darkness and helping him find redemption.
Du Mengxi, unaware of the system, has also experienced a return to the past. In his previous life, he was betrayed and killed, only to realize after his death that his nephew, Jiang Yun, had sacrificed himself to save the young boy. Driven by guilt and love, Du Mengxi resolves to protect Yun'er in this lifetime. He arrives at the hospital to claim guardianship, overriding the objections of the Jiang family patriarch, who dislikes the child due to his association with the gang. Du Mengxi takes Jiang Yun to his estate, where the boy begins to adapt to his new life under the care of his uncle and the gang's loyal lieutenant, A K.
The core conflict revolves around Jiang Yun's dual existence: he is a grieving child seeking parental figures while simultaneously being the agent of a system tasked with altering the fate of a dangerous crime lord. As Jiang Yun settles in, he faces health challenges due to his premature birth and weak constitution. The system uses points to sustain his life, creating a pressure for Jiang Yun to complete tasks efficiently. One early task involves intervening when the family doctor makes a medication error. Jiang Yun pleads for the doctor's mercy, earning points and preventing the doctor from being fired, which inadvertently alters the timeline by keeping a potential romantic interest for Du Mengxi in his orbit.
Du Mengxi observes Jiang Yun's unusual behavior and intelligence, noting moments where the child seems to anticipate events or communicate with an unseen presence. He discovers the system's light ball but chooses not to expose it, instead using his own resources to ensure Jiang Yun's safety and well-being. He replaces a cherished teddy bear that was discarded by the Jiang family, installing a tracker to monitor the boy's location at all times. The relationship between uncle and nephew deepens as Du Mengxi provides the affection and attention Jiang Yun never received from his cold grandfather. Meanwhile, Jiang Yun navigates the dangerous world of the Qinglong Gang, trying to balance his childish desires with his urgent mission to save the man who is becoming his new father figure. The story sets the stage for a complex dynamic where the villain seeks to protect the child, and the child seeks to save the villain, all while the system monitors their progress toward changing the predetermined tragic ending.
