Liang Yuan, codenamed "Observer", was once the top human experiment expert of a mysterious organization. Three years ago, he was forced to fake his death to escape due to an experiment that went out of control. He became an ordinary single father incognito and lived a peaceful life with his five-year-old son Liang Xiaobao.
However, a darkened experimental subject - a mad scientist codenamed "Zero" - crawled out of the ruins of the laboratory and began to replicate Liang Yuan's experiments on a global scale, using extreme means to test the bottom line of human nature. What's even more frightening is that "Zero" discovered that Liang Yuan was still alive and decided to let him watch his experiment be pushed to the extreme.
Liang Yuan was forced to return to the world. On the surface, he is a gentle dad, taking his children to and from school, making lunches, and putting them to sleep; secretly, he uses more sinister methods to counter "Zero's" experiment, using psychological traps to solve the difficulties set by the other party. What he wants to protect is not only his son, but also the world that is about to be overturned by human experiments.
But Liang Yuan soon discovered that there was a bigger black hand behind "Zero" - a mysterious organization that used the humanity of hundreds of millions of people to conduct experiments. And there seems to be a bigger secret buried between him and his son...
