Takeout delivery guy Lin Xiaohai was originally an ordinary working stiff, but on his delivery route he accidentally awakened the bloodline of the Mountain Guard, becoming the city's only Shanhai duty officer. Boss Bai of the ancient auspicious beast convenience store who clocks out on time and never works overtime, and Grandpa Zhou the hidden bigwig security guard who loves squatting in the security room drinking little cups of liquor, total up the whole department to just three people. Delivering takeout by day to earn meal money, capturing exotic beasts and patching up barriers by night, until he investigated and found out—his grandfather who had been missing for twenty years was actually the realm-breaker that the whole city was chasing.