Sébastien roams the mountains at will, seemingly in preference to school, and it isn't long before 'The Beast', a Pyrenean Mountain Dog, and he meet up. The dog, which is wary of adults, forms a bond with the child, and Sébastien does everything he can to protect his new friend.
All this is taking place during the Second World War and German soldiers are posted in the village, their orders being to catch Jews who they suspect are being led across the mountains to Switzerland by the local doctor, Guillaume. Angélina, César's daughter, is the village baker, and cares for her father and Sébastien.
Belle is injured by hunters and Sébastien convinces Guillaume to treat her. In time Guillaume will realise that Belle isn't the Beast, but not before he comes to rely on her after he injures himself defending sheep from a pack of wolves; the real 'Beast'.
There is also, of course, interaction with the German soldiers, one of whom being particularly attracted to Angélina. His feelings prove to be a salvation for Angélina when she and a group of Jews are pursued by soldiers as they try to cross the mountain.
This is a charming story set in the most picturesque of locations.