Remember the opening of the first Iron Man film? We see a convoy of trucks crossing a desert valley. There is a moment of quiet; and then, the massive, unmistakeable crunch of AC/DC’s “Back in Black”. It plays as a clear statement of self-confidence: this film, we realise, knows exactly how impressive it is, it knows that we are going to love it (or it doesn’t care if we don’t), and it is going to be bold about it. At the beginning of Iron Man 3, we hear Tony Stark speaking, at first very seriously, and we see images of his creations being destroyed. Then, just like the first time, a song begins. But this time it’s not AC/DC. It’s a certain charmingly awful pop hit from the ‘90s that probably counts as the song you would least expect to appear in any Iron Man film, ever.

Thus does Iron Man 3 signal its intentions. It is ready to turn our expectations on their heads, and it is capable of shifting gears very quickly. And above all, just like the first film, Iron Man 3 relies on the assumption that its audience is on its side. “I’m different now,” Stark comments at the end of the flashback that follows this opening curveball. “I’m … well, you know who I am.” And there, once again, is that crucial self-confidence. We know this character, we know this world, and the film knows that we know. Director Shane Black is in full command, and he’s willing to take a lot of risks. He knows we’re ready to go along for the ride.

Iron Man 3 is everything that The Avengers should have been: intelligent, funny, relevant, surprising, cathartic. In it, Stark (Robert Downey Jr, as ever) challenges a terrorist called the Mandarin (a superb Ben Kingsley), and simultaneously gets drawn into a confrontation with a bio-engineering corporation known as AIM. The two villains pretty quickly turn out to be working together, and Stark, who is suffering panic attacks in the aftermath of what happened in The Avengers, finds that forgotten people from the wild days of his youth are suddenly becoming very, very important. His home is destroyed in a spectacular raid, and his girlfriend Pepper Potts (Gwyneth Paltrow) is nearly killed, after he commits the kind of basic, selfish, impulsive error that makes him such a compellingly flawed character. Then he finds himself alone, without any of his suits, in the middle of nowhere, and he has to pull his life back together with nothing but his courage and his ingenuity.

This film shows us how Tony Stark copes when he’s totally, irredeemably out of his depth. Forget Nick Fury and that laughable flying battleship; this is one man fighting for everything he cares about, with barely more than the clothes he stands up in, while he’s desperately trying to keep the lid on some severe emotional turmoil. Robert Downey Jr brings the character’s humanity and vulnerability to the fore, perfectly conveying the insecurity that has always made Iron Man the most interesting Marvel superhero. Tony Stark skids all over the emotional map, tipping in an instant from laser-beam focus into reckless abandon, because frenetic, non-stop motion is the only way he can keep himself going and still ignore the fear and confusion sizzling just under the surface.

Iron Man 3 is constantly surprising us – there is barely a moment when it is possible to predict what will happen next. The dialogue is loaded with wit, the action scenes are as good as you would expect from Marvel, and the special effects manage to be first-rate without ever distracting us from the story or the characters. Most memorably, the first half of the film gives us the most frightening villain of the trilogy; and then the second half does something even better. I cannot say more, except to note how good the Iron Man films are at tapping into the fears and preoccupations of contemporary America. The first film showed us war in the Middle East, and asked us to fear a group of dark-skinned men in a desert cave. Now we are five years on, post-GFC, and this film reflects the way in which power and villainy are now being understood to be more complex than was once thought – and how the true source of both is often hidden.

Tony Stark is set to appear again in the second Avengers film, but in the meantime this film provides a fitting and fulfilling closure to his personal story. Iron Man 3 is blockbuster entertainment par excellence, and it’s one of the best films that Marvel has ever produced.