A robot named Electronic escapes from Professor Gromov's laboratory. The robot looks exactly like Sergey (Serezha) Syroezhkin, a boy from a magazine cover, who was chosen by Gromov as a model to construct Elektronic.

By coincidence, the double meets its prototype. 6-grader Serezha cunningly suggests that Elektronik should impersonate him - go to school instead of him and even live in his home. His plan works, as no one can tell the difference between them. Serezha's teachers delight in a very gifted pupil, who suddenly shows unbelievable talents in math, gymnastics, drawing and even singing. Sergey's parents do not suspect his trick and are glad of their pseudo-son's progress.

However, eventually the boy realizes that as the robot takes over "his" life, he may be out of business...

At the same time somewhere abroad, a gang of criminals operates. It is headed by a criminal authority known as Stump. He tells Urrie, the gang’s most skillful member to find and kidnap Electronic. They want to organize the "crime of the century" with the use of his extraordinary abilities