The advent calendar takes place in the small port town of Jullerup Færgeby. The children Anton, Kaja and Knud live in the lighthouse, but every day they row into town to enjoy themselves with Vera and the newcomer Jonas, called 44. They find a treasure map with a strange rhyme, and supported by the old Captain Guus, they go hunting in the city for the treasure. However, the treasure hunt will not be easy, because partly the duties of everyday life and Christmas must also be taken care of, and partly the treasure map's rhyme is difficult to figure out, to say the least.