Biegga the husky is told the story of the sisters of the marsh, Cloudberry and Bilberry. One of the sisters disappeared mysteriously a long time ago, and after that, a large reindeer has been seen by the forbidden border of the marsh. Is that strange creature somehow connected to Cloudberry and Bilberry?
While pondering this mystery, a young reindeer quite literally bumps into Biegga. This is Rambler, and he is looking for his own lost brother. Together, the husky and the timid reindeer go on an adventure to the marsh filled with autumn colours. But before that, they have to meet autumn's guardian and the Willow Grouse King who loves to swing. Can Biegga and Rambler solve the mystery of the marsh and find those who are lost? And who on earth is whispering in the treetops?
Biegga and the Sisters of the Marsh is an homage to the vast untouched marsh areas in the north and the folktales belonging to them. The third independent story in the Biegga and the Guardians of the Seasons series tells about the importance of siblings and celebrates northern autumn — a season which heightens nature to its splendour with is colours, music and exceptional beings!