The protagonist of the series "Seafarer" is a simple young girl from the Russian seaside town, Katya Goloborodko. Her father is an experienced sailor and the owner of his own boat with the symbolic name "Assol". Only at the helm of this vessel does she truly feel happy, and she has more friends among the dolphins than among people. But one day, Katya receives a marriage proposal from the most eligible bachelor in the district, Sergey Galibin. Meanwhile, a dead dolphin is found on the coast.