Wang Peng uses two mobile phones and two computers and has eight online identities in more than 20 different chat groups. He's a police officer pretending to be a drug user, and he needs to put on a convincing performance.

Wang, which is not his real name, is the captain of the eight-member anti-drug team in the Tianjin Public Security Bureau.

As drug dealing is increasingly organized online in China, police are targeting chat groups and mobile social applications, which have been the main battlefield for drug control.