Lin Ye, an ordinary college student, accidentally broke into the rift zone where the two worlds meet. When he was chased by the vicious beast "Shadow Wolf", he formed a temporary contract with the injured king-level beast "Qingluan", and was involved in the hidden world where humans and alien beasts coexist. He has a rare "stainless physique" and can establish a contract with any alien beast without being backlashed. He was forced to join the "Special Affairs Bureau" that handles alien beast incidents, and learned to control power from Zhao Yan, a senior alien beast envoy.
As cracks in many places expand and alien beasts get out of control, Lin Ye and Qingluan discover that the mastermind behind the scenes, the "Soul Eater Society", is destroying the balance between the two worlds by plundering the cores of alien beasts. During this period, he met Qin Feng, a "demon hunter" who advocated the eradication of alien beasts due to the murder of his family. The two had constant conflicts due to opposing ideas, but were forced to cooperate in the process of tracing the "Symbiosis Contract" stone tablet. The nine-tailed fox illusion test in the ancient tomb, the truth about Qingluan's past as a "Gatekeeper", the ultimate conspiracy of the Soul Eater Society in the "Eye of Kunlun"... Layers of fog are revealed, Lin Ye and Qingluan use the power of "symbiosis of fate" to prevent the disaster, but also allow legendary beasts to awaken. In the end, human society gradually accepted the existence of alien beasts, and Lin Ye became the new "gatekeeper", guarding the balanced new order with the reconciled Qin Feng, while the greater unknown has just emerged.
