Forty years ago, in the dark of the playground, two children's lives were changed for ever.  The case of six-year-old Sarah Ferris, killed in an empty playground, haunted Hammersmith police for decades. Not just because the victim would never see her seventh birthday. But because solving the case meant arresting another child on suspicion of Sarah's murder. Now, forty years later, cleaner-turned-detective Stella Darnell has unearthed new information about Sarah and her killer. As Stella pieces together the truth about what happened all those years ago, she is drawn into a story of jealousy, betrayal and the end of innocence. A story that has not yet reached its end..