There is nothing one critic can say that will sway the concrete will of a One Direction fan. You might as well head to the Vatican and try to talk the pope out of being Catholic.

You can see it on the faces of the devotees in the documentary "One Direction: This Is Us." The boy band/tween girl bond transcends any disapproving parents' claims that the music is mediocre and certainly the words of one movie reviewer.

But know this to be true: "One Direction: This Is Us" is not a good film, even grading on the curve of the self-produced infomercials disguised as musical bio-pics that we've seen in recent years. The Katy Perry movie was this genre's "North by Northwest." "Justin Bieber: Never Say Never" offered insights and some drama along with its marketing pitch. The 3-D 1D movie is aimless, seemingly deceptive and spreads a poor message: It's OK to act extremely immature, as long as you have millions of blind followers who think it's cute.

There is, no doubt, a good story behind One Direction. As band members enter their 20s, do they worry about satisfying their aging fan base? Do they want more creative input in their music? Is there a "Hunger Games" thing going on within the band, knowing that only one member, if lucky, will make the Timberlake-esque turn to sustained adult stardom?

We get almost none of that here. Instead, the documentary sticks to a simple message. 1. These boys are incredibly talented; and 2. They're really just like you and me!

Never mind that almost every action in the movie contradicts the twin talking points. Pound the message hard enough, and maybe no one will notice that only one of these boys has a notable voice, and their idea of a bold creative step is "Let's all wear orange tonight!"

"One Direction: This Is Us" spends a few minutes covering the band's genesis as castoffs from TV's "The X Factor"; producer Simon Cowell himself offers a band history that seems more serendipitous and far less calculated than the likely reality.

Then we're on the road, following the band as they're alternately wide-eyed and rascally. Morgan Spurlock directs, but other than a few self-conscious touches — a neuroscientist is brought in to explain the draw of One Direction — his documentary style appears to be neutered by the demands of the marketing machine. Each of the band members takes his shirt off at least once, as if a checklist was involved.

The strategy is to hype the boys with narration, while their own words remain humble. We hear outside forces compare the band to the Beatles. But with their juvenile antics and exaggerated cluelessness, the Monkees is a more apt (and still charitable) comparison.

If one sincere thought comes through in the One Direction movie, it's the idea that fame can be fleeting. Sing every pop song like it could be your last.

Peter Hartlaub is the San Francisco Chronicle's pop critic.