The best thing about "Ant-Man" is that, for much of its running time, it doesn’t seem like a Marvel Comics superhero movie. The worst thing about it is that it eventually does. Sooner or later, men in skintight suits are shown doing battle, probably to save humanity or something like that. But even then, the action remains close to human scale, or at least closer than usual.

So "Ant-Man" is a strange case, a superhero movie that might appeal most to people who would never go see a superhero movie. At the same time, it just might disappoint audiences who see the name "Marvel" not as some unfortunate movie phase we’ll just have to live through, but as a stamp of cinematic excellence.

The first clue that this is going to be a different sort of Marvel movie is that it’s directed by Peyton Reed, whose stock in trade is comedy and whose 2003 movie, "Down With Love," was one of the shrewdest satires of the previous decade. From the beginning, the rhythms are comic and the tone is arch.

‘ANT-MAN’ Rated: PG-13 Opens Friday

The second clue is the casting of Paul Rudd, a comic actor who is refreshingly unheroic, but also not a nerd in need of superhero transformation. He’s normal, only a little funnier than most people. At the start of the movie, he is being released from prison, having used his computer genius to steal money from a huge corporation and divert it to customers. In other words, he is already a Robin Hood.

Like a lot of superhero movies, "Ant-Man" attracted some strong talent. Unlike most of them, "Ant-Man" doesn’t leave the actors looking like greedy sellouts leaping on a paycheck. Michael Douglas plays scientist Hank Pym, who, already in 1989, invented the molecule-crunching formula that allows the possibility for Ant-Man to exist. He must have been a genius, because 26 years later his protege (Corey Stoll) is only now catching up, and he plans to do precisely the thing that Hank refused to do — sell the discovery to defense contractors.

For a surprising length of screen time, the science fiction is relegated to the periphery and "Ant-Man" is just the story of Scott Lang (Rudd) and his problems. Released from prison, Scott can’t find a job. He can’t pay child support. His wife (Judy Greer) won’t let him see his daughter, and her new boyfriend (an implacable Bobby Cannavale) is blocking the door. He realizes he may have to turn to crime just to get enough money to survive.

This first section doesn’t feel like a prelude, but like the substance of the entire picture. So when "Ant-Man" finally takes a Marvel turn and starts reminding us, at first subtly, that it’s a superhero movie, the first thought is, "Oh no, why did you have to go ruin it?"

The film’s greatest virtue isn’t that it’s a superior comic book movie, but rather that it comes close to not being that at all. Close, and yet not close enough.

By the way, it should be said what Ant-Man is and what he can do. Wearing his special suit, he is capable of shrinking in size and then growing back to normal size in the blink of an eye. This can be useful in a fight. The shifts in size, as well as Ant-Man’s ability to make other objects grow and contract when necessary, make for some clever action sequences and funny moments.

Yet one of the best sequences isn’t funny at all. It comes when Scott visits the land of subatomic particles. Something in the rendering of that, with light bending and folding, exploding and re-forming, really does evoke an unseen world, something splendid and terrifying at the heart of things. It’s an unexpected and deepening moment in an otherwise lighthearted movie, and it rounds out the experience.

Review by Mick LaSalle, San Francisco Chronicle