GCHQ Puzzle Book II

Train your brain with these fiendishly difficult puzzles, the perfect companion for anyone wanting to keep their mind busy

''Fiendishly tricky'' Daily Mail

With their first bestselling book, The GCHQ Puzzle Book, the UK''s intelligence and security experts tested us with puzzles, codes and real-life entrance tests from their archives.

Now, they are back with a NEW collection of head-scratching, mind-...