Last week, I read an article that asked if it was immoral to use a dead person’s performance to ‘sell’ a film. The dead actor in question was Heath Ledger and the film The Dark Knight. Having seen it, I have no idea how you could publicise or discuss this film without reference to the very talented actor who met an untimely end earlier this year. It’s his film, and his character, The Joker, is central to it – it would be like trying to describe the Houses of Parliament without mentioning Big Ben.

Equally clamorous is the debate on whether he should be Oscar nominated for this role or if the discussion is happening merely because he died. Believe me when I say that we’d be talking about it even if he were among us in rude health, as it’s a towering, brave performance, from an actor with the safety off and unafraid of how he appears.

The Dark Knight is an excellent film and deserves the widest possible audience. However, there are two major factors that may mitigate against that: its running time is roughly two and a half hours and it is very, very, very violent. That violence is central to the film (and Christopher Nolan’s re-imagining of the series) and its themes of temptation, justice, redemption, insanity and honour, and is never gratuitously gory, but equally it doesn’t flinch away from showing you the consequences of what happens.

This is not the camp TV series or the even more camp Joel Schumacher versions. Evil is not wacky and funny and easily vanquished. It is unrepentant and potentially lies in every man’s heart, and one man’s justice is another’s evil. At its most basic, the story of Batman has always been about a fight for supremacy and a fight for justice and redemption, and, as we discover, not every villain is interested in money or power – The Joker here just ‘wants to see the world burn’. He has no limits and there is no bargaining with him.

We think we know where we are when we first see his face, smeared with half-clown, half-Whatever Happened to Baby Jane horror make-up. Just a freak. But we discover very quickly that there are no limits for this guy, possibly the greatest horror of all. There’s a tremendous stillness to the character, which is profoundly unsettling, and Ledger imbues him with a voice and a range of mannerisms that further set us on edge. He owns the screen whenever he’s on it.

Around this central villain range the Dark Knight and the White Knight of Gotham: Bruce Wayne/Batman and DA Harvey Dent. Wayne is happy to accept the mantle of vigilante if that’s what it takes to protect his city, but he knows that the public needs a public face, someone to believe in and the upright and decent Dent is just that. Both are in love with the same woman and both are pushed to the edges of their sanity, but only one doesn’t fall (fans of the comics will know the sad fate of DA Dent).

Aaron Eckhardt is excellent as Harvey Dent, his square-jawed blondness making him the perfect knight. His fall is truly poignant, aided by spectacular prosthectics/CGI that don’t overshadow the human underneath (and I still have no idea quite how they did it).

Returning from the first film is Christian Bale as Bruce Wayne/Batman, who continues to give a nuanced performance that differentiates between his two alter egos and the idiot playboy persona Wayne uses to deflect suspicion. His interplay with Michael Caine as Alfred, Gary Oldman as the last honest cop Gordon and Morgan Freeman as design genius Lucius Fox (all a delight) is superb and full of warm affection and humour.

Maggie Gyllenhaal replaces Katie Holmes as Wayne’s love Rachel Dawes, who, unable to wait for Wayne to resolve his need to be Batman, has begun a relationship with Dent. She brings beauty and intelligent feistiness to the role and it’s easy to see why both men would fall for her.

For the gadget heads, there are lots of toys (yes, the Batmobile and the Bat bike are back) – including some inventive uses of mobile phones and spectacular ways to get in a plane – explosions and action. But they serve the plot rather than being the point of it – Sam Raimi take very careful notes.

It’s definitely an E ticket ride, but don’t say you weren’t warned about the violence…

The Dark Knight opens everywhere on July 25