Six-year-old Leo leaves the secluded mountain crags where wild mythical beasts nurtured him from infancy, carrying only a primal instinct to locate his birth kin. Wandering into unfamiliar lowlands, he rescues a young girl named Greta from danger. Grateful for his intervention, Greta pleads with her mother Freya to adopt the ragged wanderer, but the skeptical matriarch turns him away, unaware of the bloodline tying them together.
Tragedy looms when the ruthless Black Mountain clan surrounds the settlement, demanding the surrender of an ancient winged beast and coercing Freya into an involuntary marriage alliance. Facing slaughter, Leo steps forward and commands the ferocious Storm Dragon King with a single whistle. As thunder crashes and the invaders scatter in panic, the boy unleashes astonishing beast-taming powers that reveal his true royal origin.
