Psychological thriller about a family with secrets...a bad daughter returns to help or hinder?

"All families have their secrets" and it appears that this family may have more than others - some of which have left them fighting for their lives. Intrigued to see what momentous incident caused 'The Bad Daughter' to leave her family in the first instance, and why she has now returned...is it to help or hinder her family in a time of need...?