A well-known treasure hunter receives two letters from the same city at once. In one, a stranger talks about a possible search for a batch of silver coins lost by a merchant clerk in the 19th century; in the second letter, the abbot of a local monastery asks for help clearing a pond from a dangerous legacy from the time of the Great Patriotic War. The treasure hunter is on vacation, it’s summer time - why not try your luck , maybe something interesting will be found, and he hits the road with a friend, not even suspecting what kind of adventure he got involved in!..