Based on the search for a flooded city, the film tells the story of three generations of underwater archaeologists, divers of the 30s, scuba divers of the 60s and robot operators from the 21st century. All of them are united by a passion for the knowledge of the past.

A film about underwater archeology and adventure. Scientists studying the Khazars suggest that a team of underwater archaeologists find an exploded and flooded cathedral in the Tsimlyansk reservoir on the Don. The temple, according to legend, was made of ancient building materials taken from the Khazar fortresses. Scientists hope to find bricks and blocks with Khazar signs to reveal the secret of what they mean.