To say that the six brothers profiled in the documentary “The Wolfpack” have had an unusual upbringing is to put it mildly. Raised in near-total isolation in a public housing complex on New York’s Lower East Side — in a run-down apartment that one of the boys compares to a prison, because of their Hare Krishna father’s paranoia about the outside world — the Angulo brothers were rarely allowed outside for most of their young lives.

Ranging in age from 11 to 18 at the time that this remarkable film was shot, the siblings seem to have learned about life from two main sources. First is their mother, who home-schooled them well, judging by how thoughtful, articulate and self-aware they come across on camera. Second is the cache of some 5,000 Hollywood movies that they own, on DVD and VHS. Several of the movies have been lovingly re-created, in home-movie versions of such thrillers as “Reservoir Dogs” and “The Dark Knight,” with the boys casting themselves in all the roles.

If this situation sounds like a recipe for disaster — let alone an invitation to child-abuse charges — “The Wolfpack” will surprise you. Although filmmaker Crystal Moselle tiptoes around the subject of psychological damage — five of the brothers are reportedly no longer on speaking terms with their father — the Angulo boys come across as astonishingly well adjusted, articulate, warm and even forgiving.

Of course, some seismic shift in the family dynamic had to occur to even make this tender, compassionate and inspirational film portrait possible. In 2010, one brother, Mukunda, then 15, slipped out without his father’s permission, precipitating regular breakouts by the rest of his brothers. It was during one of these unauthorized excursions that Moselle, a first-time feature filmmaker, met and befriended the boys. Oscar, the Angulos’ father, barely appears in the film, coming across as still weirdly reclusive, if chastened.

Much of the film takes place within the four-bedroom apartment where the boys live, though one is shown moving out toward the end. Moselle intercuts footage of the brothers’ filmmaking exploits with one-on-one interviews with the teens and their mother, Susanne, who, since filming was completed, began using her maiden name, Reisenbichler. A daughter, who is developmentally disabled, is largely absent.

The setting of “The Wolfpack” is claustrophobic to be sure, but the space appears larger than it sounds, filled as it is with the boys’ seemingly boundless creative energy. One brother shows off a convincing Batman suit fashioned out of cereal boxes and yoga mats. Movie scripts were transcribed by hand, using the pause button of a remote control to stop the action and write down dialogue.

But in addition to the crazy artistic foment, there is also big, big love in this place.

More than a testament to the power of cinematic storytelling as food for the human spirit, “The Wolfpack” also is a portrait of a family that has had to rely on each other to survive. The circumstances may be extreme. But as becomes obvious during scenes near the end of the film, when the Angulos are shown visiting the beach at Coney Island and an apple orchard, the brothers’ bond is extreme as well.

Despite the nickname the boys chose for themselves — the Wolfpack — they don’t resemble those apex predators at all. In this disturbing yet uplifting true-life fable, they’re much more like exotic, yet oddly hardy, hothouse flowers.

R. At Landmark’s E Street Cinema. Contains some coarse language. 89 minutes