This story starts out with a brother and sister about how their parents are dead, their stepmother abuses them and they only get bread crusts while the dogs get the good stuff. So he takes his sister and runs away.
On their way, the brother drinks water from the stream that was cursed by his stepmom, who is a witch, and he turns into a black buck.His sister bawls her eyes out and they go to live in the cottage.
They are discovered by the a king who marries the sister and lets the deer run around the place.
When the witch stepmom hears about this, she is not happy. And neither is her birth daughter - who was by the way one-eyed. Somehow , she devises a plan to lock up princess in a lonely cave,