Colin is 9 years old and he is a little city dweller like the others. However, the activity of his grandparents, animal filmmakers, intrigues him. On his days off, he goes up to see them in the heart of Gran Paradiso National Park. It is then another school that awaits him. Colin learns to be discreet, to recognize tracks, to walk with crampons, to bivouac at altitude. A beautiful family bond is formed. But an animal is missing. To see it, the young boy puts his grandfather to the test.