Seventeen-year-old Artyom is invisible in the family and a rebel in the technical school. He has a best friend, Kostya, and they do all the provocations and antics together. When the management of the technical school draws up an unofficial list of dangerous teenagers - "explosives", Kostya, by pure chance, falls into the first place, which makes him popular among other students. Kostya revels in interest in himself - and betrays his friend, convincing his classmates that he, Kostya, is the main and only inspirer of all their tricks. Then Artyom decides to prove who the "number one bomber" really is here. But on his way, a girl, Kira, unexpectedly appears, who is able to influence his dangerous plan.