The story is about a shipping company which conducts cruiseferry traffic on the Baltic Sea between Stockholm in Sweden and Turku in Finland. It takes place on board MS Freja, the exterior of which was portrayed in the series by the Finnish registered MS Birka Princess. In the series the ship has different funnel colours from the ones in real life; in reality they were blue, yellow and red but in the series they were retouched to appear as different shades of blue. The show follows life on board the ship, mostly focusing on the crew and captain, but also on some of the passengers. The plot often involves love, breakups, accidents, deaths, murders, smuggling, theft, arson, rape, drugs, and insanity.
Another part of the story takes place on land, following the life of the Dahléns, the capitalist family who owns and runs the shipping company. There are also rival capitalists who try to gain control over the company, which leads to a constant struggle for power.