Renee Zellweger is dazzling as Judy Garland! With Oscar-caliber dexterity, she captures the tragic strength and vulnerability of the legendary singer — her wit and warmth, along with the charismatic emotionality of her voice.

Based on Peter Quilter’s play “End of the Rainbow” and adapted by screenwriter Tom Edge, Robert Goold’s sad film focuses on fragile Judy’s final London concerts before her death by overdose in 1969 at age 47.

By that time, she has already yielded to perpetual substance abuse, so it’s not a pretty picture.

Financially forced to leave her two young children (Lorna, Joey) with their father, Sid Luft (Rufus Sewell), notoriously unpredictable Judy accepts a series of dates at the Talk of the Town nightclub in London, where, out of loneliness, she marries her fifth husband, young pianist Mickey Deans (Finn Wittrock).

There are spellbinding glimpses of Zellweger on-stage as Judy, poignantly singing “You Made Me Love You,” “The Trolley Song,” “By Myself,” “For Once in My Life,” “Come Rain or Come Shine” and “Over the Rainbow.”

Gaunt and haggard, Zellweger’s world-weary songbird is broken, and stylized flashbacks reveal why.

As eager Frances Gumm (Darci Shaw), her life was totally controlled by tyrannical M.G.M. mogul Louis B. Mayer (Richard Cordery), who dictated what she could/could not eat, whom she could date and when the fake “photo op” for her 16th birthday would occur.

Ultimately, it’s a tragedy, chronicling how a talented teenager was abused and exploited, tormented to seek affection and approval from strangers in order to feel any self-worth. A quote from “Oz” author L. Frank Baum notes: “A heart is not judged by how much you love; but by how much you are loved by others.”

As a cinematic chameleon, Zellweger has progressed from a lovable ingenue (“Jerry Maguire”) to romantic comedy (“Bridget Jones”), musical star (“Chicago”), twangy Southern farmer (“Cold Mountain”), sinister tech mogul (Netflix’s “What/If”) and now iconic Judy Garland.

On the Granger Movie Gauge of 1 to 10, “Judy” is an erratic, yet empathetic 8, marking the 50th anniversary of her death.

Susan Granger has been an on-air television and radio commentator and entertainment critic for more than 25 years. Raised in Hollywood, Granger appeared as a child actress in movies with Abbott & Costello, Red Skelton, Lucille Ball, and Lassie. She currently resides in Westport.