The thing about being Liza Minnelli in 1972 is that you weren’t just the daughter of Judy Garland and Vincente Minnelli. You were 26, supernaturally talented, and close friends with Bob Fosse, John Kander, Fred Ebb, and Halston.

And 1972 was a watershed year for all of them. Fosse and Minnelli would both go on to win Oscars for their work on Cabaret, the 1972 screen adaptation of the musical featuring an iconic Kander and Ebb score; when Liza accepted her best-actress Oscar that following spring, she wore a dress by Halston. With Cabaret still playing in theaters that fall, the quintet debuted another collaboration that brought Broadway to television in a way that hasn’t been matched since. Turning 50 this month, Liza With a Z presented a new avenue for natural showbiz genius, paving over the classic American Way (hollow smiles, jazz hands, Jackie O.’s pillbox hat) with a sexy-sinister grit (disjointed hip thrusts, disco hedonism, visible sweat).

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In our days of iPhone concert footage and carefully image-controlled music documentaries, it’s hard to imagine that a television concert ever held cinematic value. And yet, even with film stock being expensive, Fosse insisted on using it. Much as his New Hollywood counterparts were invested in legitimizing rock music through cinema, Fosse had already established his interest in collapsing the line between film and theater. His screen adaptations of Sweet Charity and Cabaret exercised complete control over every last elbow jerk and where the audience focused, but they were still held to narrative plotlines. Liza With a Z gave Fosse the opportunity to recreate pure theatrical experience on film.

The first number, “Yes,” is classic Liza: big, brassy, an open-armed invitation to her audience. But the second is where the show really begins. She’d recorded the Billie Holiday standard “God Bless the Child” on her New Feelin’ album two years prior, but this was something else: an announcement of intention. With the audience already in the palm of her hands, she crescendoed the final moments of the prayerful song.

“Mama may have, and papa may have, but God bless the child who can stand up and say he’s got his own.”

No kidding. Liza sings with an abandon that’s hard to describe, and almost impossible to emulate. You might hear that final “own” and think it’s just a belt or a scream. It’s somehow both, yet neither, somewhere between unrestrained and exacting; the stuff of instant legend. That characteristic mix of abandon and precision with which she always seems to perform is in full display throughout the special—sorry to your favorite chanteuse, but most wouldn’t dare attempt a vocal performance this big as the second number in their one-hour all-singin’, all-dancin’ special.

And then comes an Oedipal shout from hell: “It Was a Good Time.” A mid-tempo Eydie Gormé song already slightly deranged in how it set breakup lyrics to an upbeat melody—“It was a good time, it was the best time, it was a party just to be near you”—Minnelli and company took it further, infusing it with searingly personal new lines about her parents’ troubled marriage, which were delivered as tainted nursery rhymes. Midway through the song:

“Here we go ’round the mulberry bush, early in the morning

…Falling down…Lon…My fair lady…

Yes, she looks a lot like him! Yes, she does but, yes…

Baby, baby, bunting, daddy’s gone a-hunting,

Daddy’s gone!

Dormez-vous, dormez-vous,

Mama will stay near you, mama will be near you,

Not your dad, that’s too bad”

Liza blows it up into full-out mania for the last chorus, clenching her fists and planting herself squarely into the “survivor” persona that would define her career (she told Rolling Stone in 1973: “That’s what I learned from mama: survival”).

Her life’s cinematic nature, plus her longtime love for choosing songs that allow her to act through their emotional narratives must have lit a fire behind Fosse’s eyes. How do you stage a walking character, how do you capture a shooting star on celluloid? The answer was in combining the proscenium and the editing bay. Fosse, along with editor Alan Heim (later awarded an Oscar for the director’s All That Jazz), reduces the curtain and the cut to their most elemental use: punctuation.

In that way, Fosse’s curtain-editing speaks to us as much as Liza does. At the end of “It Was a Good Time,” as a faux-angry (?) Liza storms backstage, three sharp-lined curtains close in on her from each side, boxing her like a camera lens would in an iris shot. “Son of a Preacher Man” is an ellipsis trailing off, with the curtain coming down twice—the first to suggest infinity, with the dancers still going strong; the second to suggest survival, only Liza remaining onstage.

If Liza was singing and Fosse was speaking, Halston was winking. His absurdly short, red-hot halter dress for the show’s middle sequence had to be hidden from Singer, the sewing machine company sponsoring the show. “When the sponsors would come around, and they’d have to let them in,” Liza told New York magazine in 2006, “Fosse would call a break. As soon as they left, we’d get back to work.” How else should one showcase those godly legs?

But, really, it’s Liza’s show. Her eyes fluttering wildly, limbs flailing, and voice reaching past the rafters into the stratosphere, she gave something very few stars have willingly given since: her all. What other performers are willing to look as silly in the name of a dance, or show themselves as sweaty and near-manic as she’s seen to be here? Her partnership with Fosse both fits and transcends his artistic pantheon of lovable, larger-than-life women. The first shot we see of her is of a boisterous, rather surrealistic cackle—a sign of true life behind that camera-ready sheen.

She tears through 10 showstoppers and a medley with the force of a 26-year-old and an eye toward the eternal star power of a grand dame. Many concert specials followed, many comebacks and celebrations, all adding to her incredible legend. She was actually given a Special Tony Award two years later for “adding lustre to the Broadway season.”

The special was broadcast on September 10, 1972, and twice more in 1973; Fosse, Minnelli, Kander, and Ebb all won Emmys for it, with three for Fosse alone. Despite all of that, it was thought lost until 1999. When film restorer Michael Arick realized its copyright was almost up, he called Liza, who owned both the rights and a copy of the negative, and they brought it back to glorious life.

Thank God. Liza With a Z remains the perfect encapsulation of not only one, but five artists at the top of their craft, exalting the form of live performance into a global event worthy of praise, adoration, and endless rewatchability.