In this contemporary story inspired by the famous characters created by Cecile Aubry, we follow 10-year-old Sebastian reluctantly spending his vacation in the mountains with his grandmother and aunt. He is to help them with the sheep, hardly an exciting prospect for a city boy like him… but that is without considering his encounter with Belle, a huge dog mistreated by her owner. Ready to do anything to fight injustice and to protect his new-found friend, Sebastian will spend the craziest summer of his life.