“Judy” is the third musical biopic to hit the big screen this year, following in the footsteps of last November’s “Bohemian Rhapsody” and “Rocketman” this past spring. The film, which covers the final months of Judy Garland’s life, clearly cares deeply for its subject, although this empathy has unfortunately resulted in a script blinded by love. Luckily, while the writing may be schmaltzy, star Renée Zellweger is brilliant in the titular role.

Most passing fans of Judy Garland know her for her musicals, whether it be the timeless “The Wizard of Oz,” the Broadway-style “Meet Me In St. Louis” or “A Star Is Born.” But by the end of the 1950s, Garland’s erratic behavior and addictions rendered her uninsurable, dooming her Hollywood prospects. Thus Garland returned to her roots, spending the final years of her life as a singer. “Judy” covers her final five-week engagement, as the headliner at the Talk of the Town nightclub in London.

By the end of the 1950s, Garland’s erratic behavior and addictions rendered her uninsurable, dooming her Hollywood prospects.

Based on the West End production of “End of the Rainbow,” “Judy” postulates that Garland was basically a human Bonsai tree, raised within the abusive talent factory of the Hollywood studio system of the 1930s and ‘40s. She’s a creature built for a world that ended abruptly in 1948, when the United States v. Paramount Pictures, Inc. ruling put an end to it by declaring the distribution system violated anti-trust laws. When we meet her, she’s shuffling from hotel to hotel and driving around by hired cars, even though there’s no longer a studio to pick up the bill. Her London engagement is supposedly a way to make money to gain back custody of her children, but upon her arrival, one can see the relief that somebody, anybody, is financing her lifestyle again.

The film itself is a strange beast. Like “Bohemian Rhapsody,” it feels more like a TV movie than a Hollywood blockbuster. The script hits all the clichés. Flashbacks to her time at MGM punctuate the proceedings, taking viewers back to the “Wizard of Oz” set and her staged “dates” with Mickey Rooney. Each memory is pointedly set up to reflect the situation at hand, not trusting the audience to make connections for themselves.

The good news is that the supporting cast is 90 percent British television stars, which makes the project feel much more like a BBC miniseries than an installment of VH!’s “Behind the Music.” There’s Rufus Sewell (“Victoria”) as Judy’s ex-husband Sid Luft, here’s Jessie Buckley (“Chernobyl”) as Judy’s handler Rosalyn, and Michael Gambon (all the good “Harry Potter” films) plays Judy’s final employer, Delfont. The filmmakers even scooped up “Game of Thrones” standout Bella Ramsay to play Judy’s teenage daughter, Lorna Luft.

The only person out of place in the lineup is Zellweger, who seems to remain convinced she’s starring in an Oscar contender. But that’s the point. Garland stood out wherever she was, an exotic bird perplexed by the park of pigeons she had stumbled into, and utterly, desperately unable to cope with it all.

And then, suddenly, she’s thrust out on stage. And that’s where Zellweger, Garland — and the film — come alive.

Unlike most current biopics, where actors don prosthetics and modulate their voices, Zellweger remains unmistakably Zellweger throughout. That’s partially out of necessity. One of the film’s subplots dives into Garland’s status as a gay icon, and as such, the last 50 years have seen literally hundreds of Garland impersonators. Rather than attempt to compete, Zellweger is fine with remaining physically herself, with a few physical mannerisms Garland was known for thrown in.

And yet, when she steps on that stage, magic happens. Zellweger stops trying to hunch down to be believably tiny. Her spine straightens and her eyes light up. For the first time, Zellweger/Garland knows where she is, and what she’s supposed to do. The insecurity, the depression and the drug addiction all fall away as Zellweger throws herself into Judy’s jazz standards like “By Myself.” It may not be an exact vocal copy of Garland’s singing, but much like the physical performance, it doesn’t really matter. Seeing and hearing Zellweger within her performance as Judy is why it works.

The only person out of place in the lineup is Zellweger, who seems to remain convinced she’s starring in an Oscar contender. But that’s the point.

From then on, the film is merely scenes strung together while the audience waits for Garland to return to the spotlight. Offstage, she makes the same mistakes over and over, including fifth and final disastrous marriage to Mickey Deans. With Deans, her erratic behavior is worsening, but on stage, she’s blowing away the world with “Come Rain or Come Shine.”

Being the sort of cheesy film that it is, “Somewhere Over The Rainbow” is saved for Garland’s finale. But Zellweger’s performance is such that it overrides the syrupy ending. It’s a testament to how incredible Zellweger is that she finds a way to shine anyway. But then again, one could’ve said the same for Judy herself.