The Wild Swans (1977)

When a king gets lost during a hunting trip, he is found by an old woman who tells him her daughter will be able to show him the way out of the woods if he satisfies her wishes. The king finds the woman to be remarkably beautiful and agrees to her request of marrying him. However, the king has seven children and the new queen soon becomes jealous as he often leaves to visit them at their secret home in the woods. With the help of a magic yarn ball, the new queen is led to the hidden tree-house where the king's daughter Elisa and his six sons live. They are excited about meeting their new mother and run to greet her, but as soon as they get close, the new queen throws white sheets over them turning them to swans, all but Elisa who manages to get away. Now that they've been turned into swans, Elisa can only see her brothers at night, when the enchantment breaks, and when spring comes, they'll have to migrate to a colder climate. Before leaving, they tell Elisa of the one way she alone could break the spell. She would have to collect nettle and spin it into thread with which to make six shirts, one for each of her brothers, for six years. During this time, she would have to remain silent, for if she were to speak a single word or make the smallest sound, they would all die instantly.