In a seaside village, fishermen have no catch and are starving. The bravest of them, Azmun, sets off to the land of the "sea grandfather" to help him. But the grandfather is angry because the fishermen have long since broken the agreement according to which they were supposed to throw small fish back into the sea. So Azmun is given tasks that he must complete in order to please the sea grandfather. He is helped by a magical fin and a clever girl. And Azmun promises that the fishermen will forever obey the laws of the sea and not just use it.