Telluride Film Festival: Renée Zellweger delivers a career-defining performance playing iconic actress Judy Garland in Rupert Goold’s penetrating and personal film, “Judy.”

“Judy” takes place in the third act of Garland’s troubled life. As she struggles to move on from a Hollywood that has thrown her aside, her ex-husband, Sidney Luft (Rufus Sewell), takes custody of their children. Desperate to win them back, Garland moves to London where she has remained a big star. Here, she tries to reignite her career performing to sold-out crowds.

Goold’s film does its job to humanize the beloved Oscar-nominated actress who struggled from life-long problems with substance abuse. Goold uses flashbacks to Garland’s time on the set of “The Wizard of Oz” under the controlling thumb of studio head Louis B. Mayer. He uses this technique to bring to light the fact that Garland’s pill-popping tendencies were brought on by her childhood in showbiz. While it helped illuminate the origins of her conflict, this approach left the viewer detached from the main attraction. The characters in the flashbacks felt one-dimensional, and did not aid in moving the film forward. A single opening scene to her youth might have done more good than the decision to go back and forth in time.

Tom Edge’s screenplay maintains a tame course rather than sensationalizing her addiction. Instead of overemphasizing here, the film chooses to highlight themes of solitude and abandonment. In this regard, “Judy” has moments that marvel. Her agony of desolation is tangible, and shows up like a wrecking ball the second anything good begins to happen for her. We never feel this more than when Zellweger performs the tune “By Myself.” This moment, along with a rather stirring final scene, is where Zellweger has never been better.

Zellweger, who did all her own singing and dancing, devotes exceptional detail and physicality in her portrayal. She magically replicates the bug-eyed gaze and crinkled forehead Garland was known for late in her career. With seeming ease, Zellweger encapsulates a woman under constant pressure since childhood, who has long battled her inner demons until she could no longer keep them from bubbling to the surface.

Prior to the world premiere, Zellweger was fetted with an honorary tribute. The film reel of her career was book-ended with moments from her performance of “Roxie” in Rob Marshall’s Best Picture-winning film, “Chicago.” She was gracious and generous with her audience, much like she was earlier in the day at the Patron’s Brunch. She openly discussed her six-year sabbatical from film, citing her need to grow as a person and create life lessons that she could draw from in her performances.

“Judy” is not short on problematic moments and is at times overly melodramatic. The flashbacks play like a broken record that skip and repeat up until the penultimate scene. This made for a sometimes choppy, sometimes brilliant movie.

The star buoys the film with a jaw-dropping portrayal. Renée Zellweger’s volcanic, tour-de-force performance is one for the ages, and is absolutely worthy of a second Oscar.

“Judy” is distributed by Roadside Attractions and is set for a September 27 release.