Do you think schools have a rest in the summer, like their students? That the corridors and classrooms are deserted, and the portraits of great minds are the only spies of the summer silence? Three teenagers manage to get the entrance key to the school, and now they have four floors of corridors, offices and stairs at their disposal. One obstacle to becoming full owners of this is the old caretaker, who hardly leaves his nook, but who keeps the keys to the rest of the premises. An innocent joke - to lure him out and steal the keys. But the joke turns into a tragedy, and the guys who meet by chance find themselves bound by a terrible secret, which becomes more difficult to bear every day.