1950s Finland, a period when boats from all over the world were docked in the harbour city of Kotka. In addition to transporting goods, the sailors brought another import: jazz, swing and blues. Some music-loving, fearless and passionate young men from Kotka decide to open Fennia, a jazz bar. Soon Fennia becomes a legend of its own time, where the men, the Harbour Brothers, play their music and hold court like emperors. "Keisarikunta", the original name of the title, means just that - The Empire. One summer, the Harbour Brothers conquer the souls of the sailors and the people of Kotka.