Iron Man 3 (PG-13)

At the start of Iron Man 3, the usually loquacious billionaire Tony Stark (Robert Downey Jr.) is off his game. Having learned of the existence of aliens and alternate universes in The Avengers, Stark is suffering from post-traumatic stress syndrome. He’s had his mind blown, and he’s having trouble readjusting. For Christmas, he buys his girlfriend Pepper Potts (Gwyneth Paltrow) a stuffed rabbit the size of a small building. When a terrorist known as The Mandarin (Ben Kingsley) starts making threats on live TV and blowing up bombs, Stark gives his home address to a news crew and challenges the villain to attack him — which he does.

The helicopter raid on Stark’s Malibu pad gives Iron Man 3 its first action setpiece and proves that Shane Black, who had previously directed only one movie (2005’s spiky comedy Kiss Kiss Bang Bang, also starring Downey), knows how to play with big toys. Black, who became famous (and extremely rich) in the 1980s for writing the Lethal Weapon series and other buddy-cop movies, proves surprisingly adept at giant-scale moviemaking. In one terrific sequence featuring some astounding skydiving stunts, 12 people fall out of a plane, and Stark, wearing his armor, can carry only four. What’s a hero to do?

Iron Man 3 could have used more dilemmas like that one, investing the action with something other than just spectacle. There are wafer-thin characters, such as the villainous entrepreneur (Guy Pearce) and the biologist (Rebecca Hall) who have created an army of super-soldiers. There isn’t enough of Don Cheadle as Stark’s fellow do-gooder War Machine, and there are way too many Iron Man suits flying around by themselves. If they no longer need to be navigated by a person, then why does Stark ever bother to risk his life and put it on?

The logic may not hold together, but Iron Man 3 is going to be huge anyway, and the reason is Downey. The Iron Man movies have always been light and comic in tone, and Black knows precisely how to write for the actor. He blends the perfect amount of tartness and wit into Downey’s dialogue, so scenes that you would normally wish you could skip over are great fun to savor, such as a long interlude in Tennessee where a helpless Stark relies on a 10 year-old boy who wants to know more about the Avengers. Just like he does with those crummy Sherlock Holmes movies, Downey elevates this rather silly material with his sheer presence: Is there any other actor working in movies right now who is as much fun to simply listen to? Iron Man 3 ends with a surprisingly generic showdown at a shipyard with cranes and explosions and fake-out deaths, but it doesn’t send you home irritated and empty, like Iron Man 2 did. Marvel Studios can draw from this well only so many times, though, before fatigue sets in.