Fancy yourself a master codebreaker? Could you have worked at Bletchley Park? Find out in Brian Clegg's puzzle book Conundrum (£8.99, Icon Books).
The chapters each have a theme, so whether you love science and maths or arts and literature, there are codes for you to crack. There's also an introduction to codebreaking for the less experienced puzzlers.
We have five copies of Conundrum to give away. All you have to do is read Brian Clegg's Desperately seeking missing matter: the search for 95 per cent of the Universe and answer the question below.
