Although the Cleves generally revelled in every detail of their family history, the events of 'the terrible Mother's Day' were never, ever discussed. On that day, nine-year-old Robin Cleves, loved by all for his whims and peculiarities, was found hanging by the neck from a rope slung over a black-tupelo tree in his own garden. Eleven years later, the mystery - with its taunting traces of foul play - was no nearer a solution than it had been on the day it happened. This isn't good enough for Robin's youngest sister Harriet. Only a baby when the tragedy occurred, but now twelve-years-old and steeped in the adventurous daring of favourite writers such as Stevenson, Kipling and Conan Doyle, Harriet is ready and eager to find and punish her brother's killer. Her closest friend Hely - who would try anything to make Harriet love him - has sworn allegiance to her call for revenge. But the world these plucky twelve-year-olds are to encounter has nothing to do with child's play: it is dark, adult and all too menacing.