李卫（徐峥饰演）是一个目不识丁的乡下人，却因为偷了十三阿哥的宝剑，而获得赏识竟然能出任一方县令，当上了父母官。故事要从康熙时候说起，一次跟随难民逃难的时候，李卫认识了岳思盈，看到百姓们饥饿难耐抢夺粮食而被官府处斩，情急之下的李卫偷偷将十三阿哥的宝剑偷出来，一次逼迫官府将百姓都放了，被紧随其后的十三和四阿哥看见，由此李卫竟然意外导航上了县令。自从当上县令之后，李卫并工资发，头脑清楚，竟然破获了不少案子，也大胆惩治了当时的恶霸，四阿哥对他更加欣赏，恰好当时出现了国库空虚的现象，李卫升职为知府，专门去负责调查扬州的盐商问题，李卫在升官的路上披荆斩棘...，岳思盈姐弟俩一直陪着李卫，帮助李卫出谋划策，每次也能逢凶化吉

Li Wei (played by Xu Zheng) is an illiterate countryman, but because he stole the sword of the thirteenth brother, he was appreciated and even became a party member. The county magistrate became a parent officer. The story starts from the time of Kangxi. Li Wei met Yue Siying when he was fleeing with refugees. He saw that the people were starving and robbing food and were beheaded by the government. In desperation, Li Wei secretly stole the sword of the thirteenth brother. When he came out, he once forced the government to release all the people, and was seen by the thirteenth and fourth elder brothers who followed him. From this, Li Wei unexpectedly navigated to the county magistrate. Since he became the county magistrate, Li Wei paid his salary and was clear-headed. He actually solved many cases and punished the bullies boldly. The fourth elder brother appreciated him even more. It happened that the national treasury was empty at that time. The magistrate was in charge of investigating the problem of salt merchants in Yangzhou. Li Wei overcame difficulties on his way to promotion... The sister and brother Yue Siying stayed with Li Wei all the time, helping Li Wei to make suggestions, and every time he was able to avert danger