Belle and Sebastian is based on a novel by Cécile Aubry. The story is about a six year old boy named Sébastien and his dog Belle, a Pyrenean Mountain Dog, They live in a small alpine village on the French side of the border between France and Italy. Sébastien lives with his adopted grandfather, sister, and brother. Sébastien's mother died after giving birth to him while trying to cross the border on Saint Sebastian's day.
News comes to a small village in the French Alps that an enormous white dog is running wild in the mountains. Sebastian is determined that it shall come to no harm.
The Shelter at Grand Baou
César takes Sebastian higher up the mountain pass than he has ever been before, and shows him the way to the Italian frontier.
Because they don't understand Belle, the villagers are terrified of her, and determined to hunt her down. But Sebastian intervenes.
A sinister newcomer to the village gets work locally, and insinuates himself into Cesar's household.
Sebastian is suspicious of Norbert, especially when he sees him meeting a strange car.
Much to the disquiet of Angelina and her grandfather, Norbert begins to exercise a bad influence over Jean.
The Big Valley
Jean tricks Sebastian and takes Belle for training up to the Grand Baou in accordance with Norbert's instructions.
The two customs men become suspicious about Belle's activity.
Angelina's plans for a happy Christmas appear to be ruined, and Sebastian goes up into the mountains in search of Belle.
The Commissioner from Paris arrives in the village just as disaster hits the chalet.
Norbert takes to flight, and Jean Is involved in the Commissioner's investigations.
Has Sebastian escaped the avalanche? And where is Belle?
Jean tries to find the evidence which will prove his innocence.