Li Liqin, the captain of our border drug enforcement team, successfully captured a group of drug traffickers with the help of intelligence provided by Song Chao, who was codenamed "Mountain Sparrow" and whose real name was Song Chao. But who was the mastermind behind the scenes, nicknamed "Night Brother"? How was her "Ant Plan" implemented? In order to completely destroy this vicious criminal gang, the superiors sent two investigators, Wei Guoming and Jin Hanyu, who, under the cover and introduction of Song Chao, successfully infiltrated the gang as the largest buyer.