Mo Xuan transmigrates into the body of a black snake. After being abandoned by the Liu family, he unexpectedly awakens a clan-guarding system, only to discover that its core functions can only be unlocked by binding himself to the heir of a prestigious family. To survive and take revenge, he hunts demonic beasts in a dangerous forest to accumulate evolution points. However, he encounters a Blazing Black Tiger at the peak of the late Qi Refining stage and is pushed to the brink of death. Just as all hope seems lost, he unexpectedly forms a symbiotic spiritual pact with Zhou Kaiding, the unconscious heir of the Zhou family. Using the pact's power, Mo Xuan advances to the late Qi Refining stage and barely manages to kill the beast. After becoming the Zhou family's guardian spirit beast, their fortunes become intertwined. As the family grows stronger, Mo Xuan gradually evolves into the mightiest of mystical beasts.