Having moved from his native village to the huge city of Lyon, the boy Tidu loses not only his old friends, but also his beloved dog - the German shepherd Kafi. Kafi mysteriously disappears. Is this disappearance connected to the daring robbery that shocked the entire city? Investigating this case, Tidu finds his Kafi and new wonderful friends, with whom he manages to expose a terrorist organization planning to blow up a nuclear power plant.