In November 1959, the archaeological expedition of Professor Teternikov died under mysterious circumstances in the Altai Mountains. In the professor's office and city apartment, the investigative team of the KGB of the USSR conducts hot searches. It soon becomes clear that shortly before his death, the professor took a unique exhibit from the storerooms of the Historical Museum for study - fragments of a Scythian shield, the bronze plates of which were covered with petroglyphs. The investigation is entrusted to Rostova.