Mid-17th century. Restless on the northern Russian borders: the new Swedish king Karl Gustav is rapidly advancing along the entire coast, threatening to turn the Baltic Sea into an internal "Swedish lake." Sovereign Alexei Mikhailovich understands that a new war with the Swedes cannot be avoided... Nikita Petrovich Buturlin, a small-scale Russian nobleman, is very concerned about his own life. His economy has long fallen into decay, there are only faithful slaves and intrigues with a powerful neighbor because of the land and forest lake. In order not to disappear at all, Buturlin trades in pilotage - he drives merchant ships along the Neva River to the Swedish city of Niena. There, in Niena, one girl lives, which Nikita likes so much... However, are they destined to be together? Moreover, the war is about to begin, and Buturlin has already received from the governor himself, Prince Pyotr Ivanovich Potemkin, a very important and dangerous task associated with the Nyenschants fortress...