Twenty-one years ago, Dr Richard Carter and his wife Pamela were murdered in what has become the most infamous double murder of the modern age. Ten-year-old Sara Carter - nicknamed the Angel of Death - spent eight years in a children's secure unit and is living quietly under an assumed name with a family of her own. Now, on the anniversary of the trial, a documentary team has tracked down her older sister Shannon Carter, compelling her to break two decades of silence. Her explosive interview sparks national headlines and journalist Brinley Booth, a childhood friend of the Carter sisters, is tasked with covering the news story. For the first time, the three women are forced to confront what really happened on that blood-soaked night - with devastating consequences for them all.