The six princes, royal sons of King Hildebrand, inhabit a secluded forest castle at their deceased mother's behest. Their existence shifts dramatically when their father, lost on a hunt, is compelled to wed Greta, a witch's daughter, to escape an enchanted wood. Consumed by jealousy, the new queen employs enchanted white cloths to curse the princes, transforming them into swans whenever they venture outdoors. Only their sister Elisa evades the spell by concealment.

Cursed as swans by day and human by night, the princes must migrate seasonally to colder regions. They seek shelter in a distant cave, where they reunite with Elisa. In their nightly human state, they disclose the curse's workings to their sister and the exacting conditions for its dissolution: Elisa must weave six shirts from stinging nettles while observing absolute silence for six years. The princes voice apprehension about the profound personal toll this endeavor exacts from her.

Demonstrating unwavering loyalty, the princes protect Elisa throughout her trial. They first harbor her in their cave and supply winter garments. Forced by migration to depart, they leave her reluctantly. Upon returning to find her missing, they embark on a search. The curse breaks when they swoop in during Elisa's execution, arriving as swans as she faces burning. Elisa hurls the finished nettle shirts at them mid-flight, triggering their permanent restoration. The cascading swan feathers douse the flames encircling her. Restored, the princes validate Elisa's account to King Friedrich, unveiling the witches' deceit. They share in the final reunion with their father and sister.