(CNN) -- According to a Russian proverb, God makes the priests. Jesters come from the devil.
Heath Ledger dominates as the Joker in "The Dark Knight" in a performance already garnering raves.
You won't have any trouble believing that aphorism when you see Heath Ledger's mesmerizing performance as the Joker in "The Dark Knight," Christopher Nolan's hotly anticipated and often brilliantly executed follow-up to "Batman Begins."
His face caked in cracked white greasepaint, his smile a grotesque red lipstick scar, kohl rimming his eyes, the Joker is a cruel kind of clown, the kind that is only interested in the last laugh.
Slouched in his purple suit, Ledger gives him a lopsided shuffle, a permanently craning neck and an insinuating, deceptively neighborly voice. But there's something reptilian about the way his tongue flicks through his pursed lips like a pickpocket. He's hungry for trouble, a maniac for mayhem -- and in Gotham City, where crime is still running wild, he can make himself right at home.
Ledger dominates this movie as a living presence, a live wire, dangerous and unpredictable. It's an astonishing performance, as extravagant and free ("deranged" might be a better word) as his Ennis Del Mar in "Brokeback Mountain" was inhibited and tongue-tied. See how Ledger made the Joker his own »
And "The Dark Knight" takes him -- and its world -- very seriously.
Even more than Batman himself, the Joker would usually scream "camp" (and has in the TV series and other movies) but Nolan refuses to go there. His Gotham is cement and glass, a "real" city not so different from what we might find in any contemporary action thriller. (Chicago doubles for Batman's metropolis.)
Unlike Tim Burton or Joel Schumacher, who directed previous Batman films, Nolan favors location work over studio artifice, and he seems determined to keep the computer-generated imagery within the bounds of gravity. Even the fetishistic attention to Batman's toys -- his suit, his weaponry and transport -- emphasizes utility and design; this is not a superhero in the supernatural sense. (He may not be a hero, either, according to the serious-to-a-fault script by Nolan and his brother Jonathan.)
"Batman Begins," which came out in 2005, was about the politics of fear, the power of nightmares. Bruce Wayne (Christian Bale) overcame his own phobia to turn fear back on the fear mongers and restore hope to Gotham.
In "The Dark Knight" (Nolan must have been tempted to add "of the Soul" to the title), the Joker might be his shadow or his evil twin. In some sick way, they need each other.
"You complete me," the Joker lisps to Batman, mimicking (mocking?) "Jerry Maguire." Watch co-stars defend Ledger »
The word is nowhere stated, but this Joker is unmistakably a terrorist -- he blows up hospitals, rigs bombs to commuter ferries, burns his own ill-gotten gains. (He even manages to put Gotham's crime syndicates under his thumb.) That makes Batman a kind of one-man Department of Homeland Security. And if he has to ride roughshod over civil liberties to get the job done -- eavesdropping on the entire city's cell phone data, for example -- then so be it.
To their credit, neither Nolan nor Bruce Wayne is comfortable with this glorified vigilante figure. However, the only legitimate alternative turns out to be a civic crusader, District Attorney Harvey Dent (Aaron Eckhart).
Dent, who carries around a double-headed coin, may seem honorable, but he was once known as "Two-Faced Harvey." With whom will he cast his lot? That's the movie's ultimate ideological battleground. iReport.com: Lining up for 'Batman?' Send photos, video
Unfortunately, if Dent gives the movie a classic character arc, Eckhart's disappointingly bland performance fails to nail the narcissism that must be the flip side to his zeal, making his ultimate about-face hard to accept.
That's the film's most obvious flaw. Whenever the Joker and Batman are in the vicinity, the movie hums with finely tuned dread and anticipation. But the longer it goes on (and yes, it does go on too long), Dent triangulates the equation, ultimately pulling it out of whack.
Still, for the most part, "The Dark Knight" is an exceptionally smart, brooding picture with some terrific performances. In a summer when action overwhelms intelligence (and even good sense), here's a movie that works on many levels. It even features the single most awesome truck stunt I've ever seen.
And though Ledger's tragic death in January can't help but cast a morbid pall over the proceedings -- and that's saying something, given some of the film's plot points -- when he's on the screen the movie lights up. It's a bravura turn. I'll be surprised if Ledger doesn't get a posthumous Oscar for it.
"The Dark Knight" runs 152 minutes and is rated PG-13. For Entertainment Weekly's take, click here.