A dark and nervy blend of good and bad

The Dark Knight is pure adrenaline. Returning director Christopher Nolan, having dispensed with his introspective, moody origin story, puts the Caped Crusader through a decathlon of explosions, vehicle flips and pulse-pounding suspense.

One of our smarter directors, Nolan builds movies around ideas and characters, and The Dark Knight is no exception. This is not new to the movie cops, but in a comic book film, they ring startlingly clear. You expect moralistic underpinnings in a Scorsese movie; in a Batman movie, they hit home with vigour.

But none of this artistic achievement denies the re-energised Warner Bros/DC Comics franchise its commercial muscle – as has been proved by The Dark Knight's worldwide box-office haul.

The film revolves around notions of the yin and yang between hero and villain and of those grey areas where social conscience and individuality collide. Nolan and his co-writer/brother Jonathan see the heroism of Bruce Wayne's Batman (a returning and very buff Christian Bale) as a double-edged sword. Cleaning up the streets of Gotham City turns the crime cartels into an even more dangerous beast that, once cornered, resorts to its own doomsday machine: the maniacally clever and criminally amoral Joker (the late Heath Ledger). And vigilante justice is nonetheless "justice" from outside the law. So who polices him?

Running for cover, the mob head (Eric Roberts) first takes refuge with a Hong Kong crime mogul (Chin Han).

When Batman takes him down, he and his fellow mobsters hold their noses and in desperation settle on the Joker, who knows no rules and plays everyone against one another.

Seemingly on the side of good are the city's white knight, District Attorney Harvey Dent (Aaron Eckhart); his girlfriend/Assistant DA Rachel Dawes (Maggie Gyllenhaal) – and, if you recall from Batman Begins, Bruce Wayne's long-time love – and police Lt Jim Gordon (Gary Oldman). But loyalties are easily dislodged by threats or money. The Joker's true purpose, besides amusing himself trying to outwit Batman, is to try and turn the white knight to his dark side.

Although very good at playing duplicitous, Eckhart never quite seems the crusader presumably intended. He will, of course, turn into Two-Face, but you sense this early.

The Joker, though, sees everyone as two-faced, even Batman, in his estimation.

When confronted by evil, what can a vigilante do but violate his own moral code?

The Joker means to push Batman beyond those limits.

With six major action sequences shot with Imax cameras, Nolan pushes his own cinematic envelope and the visual-effects action looks like it's happening on the streets and not in a computer.

Bale again brilliantly personifies all the deep traumas and misgivings of Batman's alter ego, Bruce Wayne. A bit of Hamlet is in this Batman.

Ledger's performance is a beauty. His Joker has a slow cadence of speech, as if weighing words for maximum mischief and contempt.

He moves languidly as if to savour his dark deeds, his head and body jerking at times from an overload of brain impulses.

Michael Caine's butler extraordinaire, Alfred, and Morgan Freeman's scientific genius, Lucius, have settled into their dutiful roles as oases of the expected when all else is unexpected.

Maggie Gyllenhaal is not exactly wasted, but she can't do much with a tissue-thin heroine.

The Dark Knight. Stars Christian Bale, Aaron Eckhart and Heath Ledger. Rated PG-13.