This film tells the story of two generations of drug police, father and son, who fought hard to eradicate drug cartels. In order to find out the mastermind behind the scenes, the protagonist Song Wentao disguised himself and got stuck in a drug trafficking area. For the sake of drug control and the safety of countless people, Song Wentao gave up his ego and staged a thrilling "Infernal Affairs". In the end, he brought the drug dealers to justice, justice defeated evil, and achieved his own growth and transformation.