This competition is now closed. Thanks to everyone who entered. Winners: K Byrne, D Glynn, D Kelly, R Lawton, J Tracey. Prizes posted 22/4.
Half Bad is "set in a modern world inhabited by covert witches, Black and White: factions divided by hatred and united by only one thing - fear of a boy descended from both sides".
Published last month, Half Bad has been translated into 45 languages, with Green breaking two Guinness World Records: 'Most translated book by a debut author, pre-publication' and 'Most translated children's book by a debut author pre-publication'.