Bolshoi principal dancer Maria Allash appears in the HBO documentary "Bolshoi Babylon." (HBO)

You’ve got to hand it to the Bolshoi Ballet. The show will go on no matter what — and “what” can include a violent attack on the ballet director that leaves him nearly blind, or the arrest of one of his dancers in connection with the crime.

Or even Russian President Vladimir Putin stepping in to purge the leadership.

Backstage at the Bolshoi, egos will flare and careers may heartlessly crash. But at the appointed hour, the curtains will part on one of the most powerful displays of performing art in the world. The Bolshoi always pulls it off.

Yet should we see the storied Russian institution as a temple of culture, or as a pit of decay burping up illusions on command? After watching the documentary “Bolshoi Babylon,” which airs on HBO Dec. 21 (9 to 10:25 p.m. Eastern and Pacific time), you may feel it’s a mix of both.

One observer in this unsettling, piercing film likens the company to a rubbish heap crawling with rats. He doesn’t mean the velveteen ones that scamper through “The Nutcracker.”

Abandon all hopes that this ballet film will take you to a place of glamour and glitter. We see that only briefly, as directors Nick Read and Mark Franchetti, seasoned journalists and documentarians, favor the hard truths behind the artifice.

Their film centers on the scandal of January 2013, when a masked assailant threw acid in the face of the Bolshoi Ballet’s artistic director, Sergei Filin. Surgeries and treatments failed to save much of his sight.

Soloist Pavel Dmitrichenko landed in prison for orchestrating the hit. His motivation? Apparently, his girlfriend didn’t get the role she wanted in “Swan Lake.”

Dancers split into factions, rumors floated of financial corruption and a casting couch — and finally a top-down cleanup. In came a new general director of the Bolshoi Theatre, the overlord of the ballet, opera and orchestra. Out went Filin.

The new Bolshoi Theatre director, Vladi­mir Urin, gave Read and Franchetti extraordinary access, and this is the chief reward of their film. The photography is intimate and dramatic, even in the near-dark backstage scenes. Rehearsal and stage shots showcase the fluid sweep and grandeur that are hallmarks of the world-famous Bolshoi style of dancing.

We hear the whispered utterances of dancers waiting in the wings, and also the unguarded statements from company officials.

“When a deputy prime minister spent half an hour telling me who should be director of the ballet,” says one, “I felt like I was in the fantasy world of ‘Alice in Wonderland.’ ”

So it goes at this theater, a mere 500 yards from the Kremlin. It’s also a line item in the state budget. Ministers, and presidents, have always meddled in the Bolshoi.

It’s not portrayed as the happiest place. There’s the constant threat of aging, for instance, or “when you become unwatchable,” as one ballerina in her dressing room laments, furiously wielding her mascara wand.

You may think you’re tearing up the stage, says another dancer, and then you find out you’re staying behind while the rest go on tour.

There are strong personalities, and egos to match. “I just walk around and people applaud me,” says Nicolai Tsiskaridze, a former dancer who had ambitions to lead the company. His clashes with Filin, in the view of the filmmakers, laid the ground for the acid attack; the dancer Dmitrichenko was one of his protégés.

“The attack emerged out of a prologue of behavior that is very Russian and mimics Russian politics,” Read said in a recent phone interview from London, where he is based. “These habits of creating cliques are very important. They don’t like things being written down, it’s all about trust and loyalty. When that is usurped and abused, the consequences can be extreme.”

People gang up on one another the world over, said Franchetti, speaking from Moscow. But only at the Bolshoi are conflicts sorted out each night, without fail.

“From the cleaners to the program sellers to the technical staff to the opera staff to the coaches to the dancers, they’re all in small worlds that are pitted against each other, and are snotty about each other.

“But,” he added, “at 7 o’clock on the dot, all these groups come together and, like clockwork, they put on a great performance. That’s very Russian.”

Yet moving the story from daily distresses to the permanent, life-altering injuries inflicted on Filin comes about awkwardly. Toward the end, the film charts this man’s further destruction, and another man’s cold triumph. This is clear in painful scenes in which Filin, wearing dark glasses that make plain his isolation, visually and otherwise, is publicly humiliated by Urin.

“I want all practices here to be completely transparent,” says Urin at one point, in a meeting with the dancers.

Unseen by him, a ballerina rolls her eyes.

Only the most talented dancers will dance, he continues.

“Then, you see, everything will be in its place.”

Should we believe him? The Bolshoi will roll forward, regardless.