Fear not. Ledger's performance in The Dark Knight is so vigorously menacing, so chillingly nutso, so insistently, gloriously alive that it is easy to forget reality for the duration of the movie, and easy to get swept along (or pulled under) by the Joker's chaotic wake. Ledger subsumes himself in a performance that is simply great, and he's loaded the Joker with tics - he's tightly wound and loose-limbed, his thick tongue flicking in and out of that sinister, wounded mouth as he bares his yellow teeth. The Joker is a chatterbox, but he looks like the wheels are constantly turning in a head that's as scary-crazy on the inside as it is on the outside. No joke: This Joker isn't kidding around.
The Dark Knight is the sequel to writer/director Christopher Nolan's Batman Begins, and like that movie, The Dark Knight entirely casts off the campy old Batman for a provocative post-millennial look at the superhero (and the superhero genre) that is far, far darker and more thoughtful. There's a genuine ambivalence at the heart of The Dark Knight (which Nolan co-wrote with his brother Jonathan Nolan) about Batman himself. Is he nuts? (Likely.) Is he just a really well-armed vigilante? (Probably.) Is he on the side of justice? (Maybe.) This Batman (Christian Bale) is like the back side of the joker cards that his nemesis leaves as calling cards: looks like all the other cards, until you look underneath. And that's the question at the thumping, moody heart of The Dark Knight: Are Batman and Joker really two sides of the same card?
The Joker seems to think so, casting himself as a self-styled agent of chaos and Batman - or "the Batman," as he is called, in a nod to Frank Miller's Batman: Year One graphic novel - as an agent of order. The Joker has no agenda, no purpose, other than creating chaos and fear. He's a terrorist for whom the only goal is to create terror.
The million-dollar question for millionaire Bruce Wayne is whether or not upholding order is the role he's meant to play. His Gotham is a city overrun with graft and corruption, with a thriving criminal underworld and with a few good cops like Jim Gordon (Gary Oldman) and a crusading, lantern-jawed new DA named Harvey Dent (Aaron Eckhardt) trying to clean things up. Onto this scene, the Joker drops fully formed, fully loaded, fully homicidal. He takes on the good guys and the bad guys, but his real prey is Batman.
As for the Batman, he's something else here too: stranger, more conflicted, more sinister, working the extra-legal beat where the moral lines get blurred. His conscience is external, located in trusted advisors Alfred the butler, played by Michael Caine, and Lucius Fox, played by Morgan Freeman. Batman does the dirty work of controlling crime, but with a joyless resignation that makes him both menacing and a little tragic - a creature who plays on our sympathies but also preys on them, exploring the darker, weaker side of human nature both in himself and in the world at large. Is he the scapegoat, the sacrificial lamb or the savior of Gotham? Does Gotham need a hero, or are we in a world where there's no room for heroes, super- or otherwise?
This is not just the story of Batman's inner struggle with good and evil, but a larger story of darkness and light, of might and right, and of humanity at a pivotal moment of choice: Do we listen to the better angels, or let the demons fight it out? When the lunatics have taken over the asylum, are more lunatics the solution?
The Dark Knight is a long, dark night - intensely violent, but also at times darkly funny. (There's a very obscure inside joke in the casting of Nestor Carbonell as Gotham's mayor: He played the cowardly superhero Die Fledermaus in the short-lived The Tick TV series.) And it is transportingly beautiful in that way that only a city at night can be, even if it is illuminated by fire. There are spectacular gadgets and stunts, massive explosions and all the other things you'd expect and want from a Batman movie; but Nolan is a director who understands and revels in the power and beauty of cinema and the cinematic image.
The Dark Knight is entertainment, but it is also art. It is pulp and it is poetry. It's a freak show, but it's a poignant and oddly moving one that turns the world upside-down and gives it a good, hard shake. The Dark Knight is heavy because it has gravitas; but it is also light because it thrills us with sights we could not, and maybe should not, otherwise see.