In one of the southern ports, state security authorities detained a spy with a plan for the object of sabotage — a floating dock, prepared for towing to a remote port. Major Lyudov, according to a number of signs, realizes that a whole group of enemies is operating in the city. With the help of Rakitina, the librarian of the floating dock, Lyudov and his assistant state security lieutenant Savelyev, they manage to unravel the tangle of espionage ties and prevent the crime.
Based on the Chinese folk tale. Long ago, three brothers Liu lived in China. They were so similar that even their own mother discerned them on colored ribbons. The first brother could command fire, the second could drink the sea and return it back, and a third knew the language of birds, animals and fish.
The Second World War. A new L-2 heavy duty gun is being supplied to the Soviet Army. German intelligence needs to seize a new secret weapon.
