Christopher Nolan's jesterpiece is so esteemed among movie lovers that we should expect Citizen Kane to start being referred to as "The Dark Knight of Orson Welles movies". It's praise, the director is always keen to point out, that should be shared among cast and crew, with production designer Nathan Crowley and costumer Lindy Hemming unsung heroes of the twilight world we're plunged into. But the undisputed MVP is Heath Ledger, the greatest screen nihilist since Little Nicky. "Why so serious?" That's why. Over a billion dollars at the worldwide box-office are testament to Ledger's towering performance as total nutter the Joker, and allowed Nolan to pretty much write his own ticket ever since.