The Dark Knight is almost undoubtedly the most ambivalent of superhero movies. Because Nolan’s film eschews the supernatural elements that are a mainstay of the genre, there is no absolute good and evil here. Instead, there are defenders and there are murderers. There are men trying very hard to do the right thing, and others trying just as hard to do the wrong thing.

Even the film’s title is a double entendre — Gotham City has been plunged into a long, dark night. Remember that Batman is an ego-driven superhero — he wasn’t forced into existence by a radioactive spider bite or some science experiment gone awry, but instead made a conscious decision to become a highly trained, dark-masked vigilante. And he remains haunted by the idea that his presence may hurt as much as it helps. Certainly, it’s only Batman’s celebrity that made his beloved Rachel Dawes a target for the Joker, who uses her death as the punchline of a sadistic practical joke that tweaks the ostensible hero for doing the wrong thing.

As I observe from the film, when Joker kidnaps both Rachel and Harvey Dent — the crusading District Attorney that Batman believes may actually be the kind of real, law-abiding savior that would finally let Bruce Wayne hang up cloak and cowl — it’s to set up an elaborate test of Batman’s moral compass. Joker tells Batman Rachel is tied up at one address, and Harvey Dent at another, forcing him to choose which of them to save before timed explosives go off. If he saves Rachel, Gotham City loses a politician with courage and a moral backbone. But if he saves Harvey, he dooms the woman he loves. (Honest politicians are apparently rare enough on Gotham City that this is a real issue.) Helplessly in thrall to his heart, Batman heads out to save Rachel, but discovers on arrival that he’s been tricked — because Joker switched address on him, his relative selfishness has actually consigned poor Rachel to oblivion.

So Batman suffers not only from the guilt of having failed to rescue Rachel, but from the shame of having been manipulated by the Joker. Not only was he nailed for making the more self-serving of the choices available to him, but he was simultaneously punished by having the only possible justification for that choice — his love for Rachel, and his willingness to continue patrolling Gotham as the Batman in exchange for her safety — stripped from him as a result of his making it. This aspect of the story is surprisingly underplayed, even confusing, but it certainly explains Batman’s decision, after Harvey Dent’s death, to take credit for the murders committed by Dent’s bitter alter-ego, the vengeful Two-Face. And it sheds some light on the Joker’s insight into humanity. Later on, when he tells the passengers on two different ferries that are scheduled to be blown up at the stroke of midnight that the potential victims on either boat can save themselves by making the decision to kill each living soul on the other ferry, is there any doubt that the detonators he gives them are wired to blow up their own boats instead?

The Dark Knight argues that it’s fairly easy to manipulate people through fear — when the Joker threatens to blow up a hospital unless an arbitrary assassination is carried out, the presumption is that anyone from the average man on the street to a cop worried about a sick relative may suddenly turn into a killer — but there are some more specific ruminations on the ease with which people can be manipulated through lies. The Joker is a liar. So is Batman, who takes responsibility for Harvey Dent’s crimes, just as Harvey had falsely claimed to be the Batman earlier in the film. Trusted confidante Alfred (Michael Caine) lies to Bruce Wayne by failing to deliver his Dear John note from Rachel after her death. Gordon lied to his family when he faked his own death. And so on. Crucially, while the Joker lies to promote chaos, the lies told by Batman and his friends are meant to preserve order.

That’s the closest The Dark Knight comes to making explicit reference to the contemporary political landscape. The science-fictional eavesdropping initiative Bruce Wayne develops to get a visual image of the surroundings of any powered-up cell phone is similar to the USA’s Patriot Act, and is itself a form of deception, or at least a betrayal of the public trust. That’s why Lucius Fox (Morgan Freeman), clearly functioning as the conscience of Wayne Industries (as well as of The Dark Knight), insists on destroying the system as soon as Batman uses it to track down the Joker. Because Lucius betrays his own principles by agreeing to play along for even a moment, it invites the interpretation that Nolan’s film advocates the use of otherwise indefensible tactics under extraordinary circumstances. But it’s clear that Lucius has compromised in his pursuit of a worthy goal, and the film assigns a moral weight to that compromise. The Dark Knight is about how hard it is to do the right thing – not least because in Gotham, as in the rest of the world, moral certitude is more difficult to reach than either idealists or ideologues would have you believe.

A self-proclaimed agent of chaos, the Joker claims he was born out of the disturbance in the mundane cycle in which the mob and the cops fought for control of the city block by block. Before Batman, came on the scene, the Joker writes himself off as nothing more than a skilled pickpocket ripping off common men and mafia members alike. Bored with his life, it could be inferred that his self induced scars were an attempt to stop having to gaze upon a veneer of depression. Spewing various origins for his scars, he makes it clear that it was not one moment that made him this way but instead a prolonged state of boredom in which he wanted to do anything to gaze upon a smile. The Batman provided him a release, someone that would let him perform depraved acts of insanity that would not reach any conclusive goal. Like the Joker says, “I am like a dog chasing a car, I have no idea what I would do if I ever caught it”. The Joker does not want Batman dead, he wants the Batman to kill him so he can corrupt the Caped Crusader’s moral code. He knows this is out of reach, because then life gets boring again. As a result, the movie becomes a mosaic of this escalated realm of heroes and villains.

“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.”