Fyodor Streltsov is a junior murder squad detective in a district Directorate of Internal Affairs. He dreams about a job worthy of a true detective: chasing, firefights, complicated criminal cases, intellectual battles etc. But his boss entrusts him a routine paperwork only.
Fyodor leads an ordinary and predictable life. He is a bachelor and lives alone (renting a room in doctor Roitman’s apartment). He rarely meets with his friends and this is enough for him.
But one day Fyodor receives a death notice of his father whom he hasn’t seen for ages. Along with this he learns about his younger step-brother Gosha’s existence. Although Gosha is only 12 he has an impressive IQ like a true genius. Fyodor refuses to take the boy but being his only relative he still has to take care of Gosha.
The boy is really interested in his older brother’s job. His shrewd observations help Fyodor solve criminal cases that seem hopeless, and Fyodor’s career is on the upswing. And from this time on Gosha will actively take part in different investigations, and little by little the brothers will get closer to each other.
Ekaterina, Fyodor’s colleague, joins them. Gosha’s deductive talent and Fyodor’s determination and courage work well with Ekaterina’s enthusiasm and helpfulness. She is an enthusiastic and frank person. Fyodor treats her as a good friend, like one of his old chaps.