Forty years ago, in the dark of the playground, two children's lives were changed for ever.
Stella Darnell is a cleaner. But when she isn't tackling dust and dirt and restoring order to chaos, Stella solves murders. Her latest case concerns a man convicted of killing his mistress. His daughter thinks he's innocent, and needs Stella to prove it.
As Stella sifts through piles of evidence and interview suspects, she discovers a link between the recent murder and a famous case from forty years ago: the shocking death of six-year-old Sarah Ferris, killed in the shadows of an empty playground.