When she was sixteen, Diana left her unhappy family and set out to make a new life. Twenty-five years later, she has arrived. Recently married to Edmund, she lives with him at his family's historic country home.

But when Diana hears that her mother has died, she impulsively asks estranged half-sister Valerie and her nine-year-old son to stay. The night of the funeral, fueled by wine and years of resentment, the sisters argue and a terrible accident occurs. The foundations of a well-ordered life start to crack and the lies begin to surface, one dangerous secret after another. And then there's the boy, watching, waiting.

The Half Sister is a profound and haunting portrayal of those who are imprisoned by their past and by the struggle to find the words which will release them.