The Christmas Reindeer. Thornton W. Burgess

Tuktu and Aklak are young Eskimo siblings who live with their father and help him with his job, being reindeer herder. One day, one of the reindeer gets lost on Tutku's watch and she goes on to search it, but gets lost in a fog of the mysterious Kringle Valley, the home of the Good Spirit where no man has ever stepped. Tutktu wakes up and meets the Good Spirit, or Santa Claus as she knows him, and gets introduced to many mysteries of the Kringle Valley, as well as Christmas tradition and Santa's duties. As she goes back to her village, Tutku has a hard time convincing her brother and father to believe her story, but doesn't give up on her dream to somehow help Santa when he goes to carry happiness and joy to all children in the world.