The series "Offline" is a detective thriller about a mysterious serial killer who challenges drug dealers. In the age of computer technology, people buy illegal substances through a special secret mobile application called BeHappy. There, they can anonymously order drugs and arrange a meeting with a courier to receive their "stash." But one day, someone hacks into the criminal internet network and downloads the database of all the sellers and buyers. The hacker demands that they themselves confess everything to the police. Otherwise, death awaits them.