This is what I did - Ann Dee Ellis

A boy is racked by guilt. His family have moved house and school to help him come to terms with a violent event at his best friend's house, to no avail. Little do they realise just how much he knows about this unspoken tragedy - and how well-placed he was to prevent it. Keeping dark secrets buried deep down is always a mistake - and when it causes you to become vulnerable to all the petty thuggery of the playground, more tragedy seems inevitable.

Told in the eleven-year-old boy's own idiom, by carefully constructed flashback, this startlingly moving cliffhanger explores every range of bullying, and every response: the ambitious dad, the copy-cat son, the mob rule of the classroom, and the benign blindness of a hapless family. It all boils down to one question: just how guilty are you, when you knew but did not say?