What do you think of this idea for a novel?

16 year old Lilac lives with her 5 year old sister, Ariel, and their abusive mother. Lilac hates her mother because of the years of psychological and physical abuse she has suffered. She struggles between deciding whether she should run away and live with her father (who lives in another city) or stay to protect Ariel. When Lilac is d and beaten by one of her "uncles" she falls unconscious and has a vivid dream telling her what to do. Lilac finally learns to stand up to her mother and she leaves home with Ariel and starts a new life on her own. What do you think? WHat can I do to improve the story?