Based on the stories The Wild Swans collected in Tales of Hans Christian Andersen and The Six Swans collected in Grimm's Fairy Tales.

Young Princess Elisa lives a happy life with her brothers in a secret house in the forest. Her family's happiness is destroyed one day when her father becomes lost in the woods and is convinced by an old witch to take her fair-faced daughter for his new bride. The jealous new queen bewitches all but one of the king's seven children, turning his six sons into swans. Elisa takes it upon herself to find her missing brothers and find a way to restore them to their human forms.

(Source: ANN)