I flicked my cigarette stub over the window and headed for my abandoned students. I found them still, like I left them, and Melinda seated at her desk.

'Okay, so where were we?'

'The sum of the natural numbers'. I looked up to where the sound had come from and the culprit was this boy whose name I can't remember, for the life of me. He looked like a miniature wrestler from the eighties, all bulked-up around his biceps, and slimy, long blonde hair, falling to his shoulders. 'But ...