September, 1945. Sebastian impatiently waits for the return of his friend Angelina, whom he has not seen for two years. When the plane carrying the young woman to her small village in the Alps is reported to have crashed in the mountains, Sebastian is convinced that Angelina is still alive. Along with his faithful dog Belle, Sebastian embarks on the most dangerous adventure of his life.

10-year-old Sebastien reluctantly spends his vacation in the mountains with his grandmother and aunt. Helping them with the sheep is 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, Sebastien will spend the craziest summer of his life.