Basic premise is that the eldest daughter of a marquess and her mother got caught up in an explosion in their border town. Her mother died, but she survived, requiring extensive surgery where the surgeon replaced an arm and eye with her mother's. 

One of the nurses helped to console her father, and by the time the daughter was aware of what was going on, they had already married and she had two step-sisters. Her fiancée, having visited her while she was recovering, informed her father that he could not go through with it with her, and her step-mother suggested that perhaps one of her own daughters could become his heir instead?

So she discovers her life has been taken over by this stranger, related by marriage, her father can't bear to look at her, talk about putting her in a nunnery, and the only thing she has to her name, really, is her mother's jewelry - much to the shock of her step mother.

Her escape and route to possible revenge is the school.