North of Tokyo, hidden between the mountains amongst frozen forests lives a creature both well known to the rest of the world and completely unique to Japan. The Snow Monkey, or Japanese Macaque is the only primate with the exception of humans to live so far north and in such cold conditions.

The documentary takes an up close look at these fascinating creatures, and explores their mysterious world and how they have learned to fight the cold. Nicknamed Hell’s Valley, the region where they live is known for it’s volcanic steam vents and natural hot springs. It’s these naturally occurring wonders that have helped provide the monkeys with an igneous way to stay warm, they learnt how to take a hot bath.