This drama film fictionalizes the relationship between two pivotal figures in the 1925 serum run to Nome: the Norwegian sled dog breeder, trainer, and musher Leonhard Seppala and his lead sled dog Togo – an exceptional Siberian Husky. The two of them endure the longest and most perilous leg of the historic effort to transport diphtheria antitoxin to an isolated small town in northeast Alaska.