Far to the north, where the cool winds blow and the aurora borealis shines in the sky most of the year, there was a small Viking village. Two friends lived there: Olaf and Freja. Olaf had red hair and bold ideas, and Freja liked to walk barefoot in the snow and could draw the most beautiful dragons on the whole fjord. One morning, as the snow creaked under his feet, Olaf came running to Freja's house with a huge brown map. It was an old map he had found in his grandfather's chest. Drawn on the map were mountains, lakes and, at the very end, a large blue spot signed: Ice Bay. "Freja! Come on, let's go there! Maybe we'll find something interesting!" - exclaimed Olaf, his eyes shining with excitement. Freja, curious, agreed at once. They packed warm skins, some cheese and dried fish, a lantern and Freja's plush dragon - for luck. They said goodbye to their mothers and rushed to the shore of the fjord, where their wooden boat stood. As they travelled through the cold waters of the fjord, a mist surrounded them and the waves gently rocked the boat. Suddenly, a huge ice boulder rose out of the water in front of them. It was all shiny, and inside it looked as if something was moving. Olaf and Freja looked at each other with wide-open eyes. As they moved the boat closer, they heard a quiet sound, as if someone was singing under the ice. At that very moment...