The Dark Knight reigns as the greatest superhero movie of all time. A wonderfully woven masterpiece, it moves at breakneck speed and remains, consistently, a joy to behold. But as the deliriously delicious script cycles through, are you ever really paying attention, or are you simply sitting back and marvelling? We're about to find out with this fiendishly difficult quiz. And where The Joker had only one question ("Where is Harvey Dent?") we have 20.