When physics teacher Jonathan Derry is unwittingly given some computer tapes containing a bookie-breaking betting system, his sharp-shooting abilities come in extremely handy against the thug who comes looking for them.

Fourteen years later, Jonathan's brother William is about to fall victim to the same thug. But this time, William is determined to play a cautious and crafty game. After all, once bitten . . .

'An extraordinary thriller . . . Evil is real here. Nails are for biting' Evening Standard