Just what it says. I hesitate to use the word "slave" because it's so bondage-y.
A powerful, evil warlord has been brought down from his tyrranical rule. He makes his escape, significantly injured, into the mountains. There, he collapses.
A young mute girl lives in the mountains, in a small shack, and has done so ever since her parents died. She lives well by herself, but one day she picks up this strange armoured man and nurses him back to health.
This isn't a story about love, redemption and romance. The warlord is still horrendously evil, and while he acknowledges that he would not be alive without the aid of the girl, he does not hesitate to use her for his own pleasure and his own ends. Morever, he needs a servant until he can plot his way back to his throne. Plus, she can't talk so she can't irritate him, can't interrupt him and can't refuse him.
Who wants to play a badass warlord?