http://monster.wikia.com/wiki/Wendigo
Your hero uses himself as bait to try to find the monster (literally or figuratively, you decide) who murdered his sister.
He finds your heroine, under the same spell that his sister fell under. How does he rescue her?
Does she really need rescuing or is she also trying to find some revenge for the death of a loved one?
What happens? Who is your villain and why is he bespelling and perhaps killing women?
Like this Story Starter? In the mood for more? Check out