Following the events of Batman Begins, Batman and Lieutenant Gordon team up with crusading district attorney Harvey Dent to crush the Gotham City mob. Desperate, the mob turns to a scarred madman who smears his face in greasepaint and calls himself the Joker. Spoilers follow.

From the opening bank robbery scene aping Michael Mann’s visual esthetic in Heat, The Dark Knight proves a different beast than its predecessor. The stagey, wooden, shantytown sets? Replaced by the striking skyscrapers of Chicago and Hong-Kong. Katie Holmes? Replaced by Maggie Gyllenhaal, who’s much more convincing as a district attorney. Awkward origin story involving far-east ninjas? Gone. This script, by director Christopher Nolan and brother Jonathan, explores the themes of duality and deception present in their prior collaborations, Memento and The Prestige.

Aaron Eckhart plays Dent, Gotham’s square-jawed white knight. An early courtroom scene epitomizes his dual nature. He stands questioning a hostile witness who draws a hidden pistol. When the gun misfires, Dent punches the witness, snatches the pistol, and dismantles the weapon. As the bailiffs drag the witness away, Dent turns to the judge. “But your honor,” he says, “I’m not done.”

This cocky exterior masks an inherent rage, evident in Dent’s quick violence. This rage emerges whenever Dent’s rendered helpless. Eckhart underplays these scenes, convincing as a man struggling to walk the line.

If Dent is Batman without a mask, then the Joker is Batman perverted. A path Bruce Wayne might have taken following his parents’ death. Like Batman, the Joker is anonymous. When arrested, his prints and DNA are without matches, his clothes are devoid of labels, and his pockets empty of everything except “knives and lint.” Like Batman, he proves incorruptible. You can’t scare, bribe, or bully him. And like Batman, he covers every contingency, always one step ahead of his adversaries. But while Batman seeks to bring order and inspire hope, the Joker brings chaos and sows fear and despair. An elemental force of chaos necessary to maintain Gotham City’s corrupt equilibrium.

As the Joker, Heath Ledger delivers an iconic performance. While past interpretations veered toward camp or manic charisma, Ledger’s portrayal adds genuine menace. His modulated delivery conveys an inner turmoil, a calculating mind battling a mindless rage. The small ticks he adds, like licking his lips between lines or running his hand through his greasy, unkempt hair, all contribute to a sense of uneasiness.

Consider the scene where he intimidates a Batman impersonator. Ledger begins with a teasing tone, “You’re not the Batman, are you?” he coos. But as the intimidation grows more violent, the man closes his eyes in fear. “Look at me,” Ledger commands, but the man proves reluctant. “Look at me,” Ledger says again. When the man still doesn’t reply, Ledger drops the teasing tone for a primal bellowing roar, “LOOK AT ME!” that feels ripped from a horror film.

Contrast that scene with a later one where Ledger’s Joker visits a near-broken Dent in the hospital. Dressed as a nurse, complete with wig, Ledger sits opposite Dent, proffers a wry smile, and says, “Hi,” with an almost embarrassed look. Nolan holds this shot for a beat, forcing a laugh. “You know,” Ledger continues, “I don’t want there to be any hard feelings between us, Harvey.” In moments like this, Ledger’s performance reminded me of Jack Lemmon as Professor Fate in The Great Race.

Expanding on the theme of duality, the film positions Dent between Batman and the Joker. Batman sees Dent as the city’s true savior. “He locked up half of the city’s criminals, and he did it without wearing a mask,” says Batman, “Gotham needs a hero with a face.”

This last line proves a nice bit of foreshadowing. In a plot line that reworks the premise behind Alan Moore’s graphic novel Batman: The Killing Joke, the Joker sees Dent as one bad day away from villainy. To prove it, he breaks Dent, turning him into the monstrous Two-Face, a visual representation of duality obsessed with the chaos of chance.

Throughout, the film weaves a secondary theme of deception, positing the sticky ethics of the ends justifying the means. First, Batman builds a covert mass-surveillance tool he leverages to locate the Joker, then he conceals Dent’s fall from grace.

And I haven’t even mentioned the assorted moral dilemmas the Joker foists on Gotham. First, he embarks on a murder spree, assassinating various city officials, claiming he’ll only stop if Batman unmasks. Then he changes his mind and declares he’ll blow up a hospital if a citizen threatening to reveal Batman’s identity isn’t killed. These ultimatums set the city on edge, culminating in a scenario where two ferries sit stranded in the bay, one carrying prisoners in transit from Gotham’s maximum security prison, and another carrying civilians. Aboard each boat is a detonator capable of blowing up the other boat. If neither explodes by midnight, the Joker will detonate both.

These escalating narrative and emotional stakes fray the bond between Batman and Gordon, setting up an unpredictable climax while making it easy to place ourselves aboard either ferry and ponder the choices we’d make. Not bad for a comic book movie.

But it’s not perfect. Three minor blemishes mar an otherwise flawless endeavor.

The first lies in Batman’s suit. In striving for realism, Nolan has sacrificed style. In close-ups, Batman’s cape looks like a cheap bit of velvet pinned to his shoulders, and his cowl’s bulging cheeks present a pear-shaped head.

The second involves a scene where the Joker crashes a fund-raiser for Harvey Dent. Batman confronts the Joker in full view of all the party guests. After the first film made a point of showing how Batman leveraged darkness and camouflage to handle large numbers of foes, this disappoints. Further, Batman dives out of the window to rescue one guest, leaving the Joker and his crew alone in a room full of Gotham’s wealthiest citizens. Rather than frame this as a moral choice forced on Batman, the script moves on, leaving us to assume everyone was okay.

But this gaffe pales next to the third misstep, a scene where Batman interrogates the Joker under bright fluorescent lights in a police station while assorted cops watch through a two-way mirror.

It’s strange that Nolan opted for this setup. When Gordon enters the room, it’s dark, lit only by a desk lamp. When the Joker stonewalls, Gordon leaves and the fluorescent lights pop on, revealing Batman looming behind the Joker. This brightly lit look at him in the suit lays bare its stylistic shortcomings. Meanwhile, a swarm of cops gets an up-close look at Batman.

Better to reverse the lighting. Have Gordon enter the bright room, then leave. Have the lights go out. Emergency lights kick in, offering perhaps a lone fluorescent. The cops scramble to restore power as Batman emerges from the darkness to interrogate the Joker, with Gordon watching through the glass. Problems solved.

Nits aside, The Dark Knight proves the rare sequel that alters the status quo. Though the film ends with Batman averting the immediate threat, in breaking Dent, the Joker has broken Gotham. By forcing him to bend his principles, the Joker has started the incorruptible Batman down a slippery slope. In taking the blame for Dent’s crimes, Batman has robbed Gotham of its incorruptible symbol of hope. In its place, Dent has become a reminder that in Gotham, no good deed goes unpunished.

This may not be the best cinematic Batman, but it’s the best Batman story and, thanks to Ledger’s performance, one of the best sequels ever made. Along with Iron Man, which premiered the same year, it ushered in the wave of superhero films that dominate cinema to this day.