You may never be able to comfortably watch “The Wizard of Oz” again after “Judy” gets its hooks in you.

Renée Zellweger gets deep inside the skin of late-career Judy Garland in a biopic from director Rupert Goold (“True Story”) that makes the savvy choice of sticking with a finite time period, rather than running through an entire life’s highlight reel.

We join the Hollywood legend as she’s scraping by from club gig to gig with her two young children in tow, having established herself as so “difficult” (read: constantly drunk and high), no one will hire her for film work. One of her ex-husbands (Rufus Sewell) is suing for custody, her kids are tired of schlepping from one hotel to another and Garland herself seems perpetually adrift — even when she’s sober. It’s a devastating performance from Zellweger, whose unique face takes on an almost ghostly resemblance to Garland’s under an aggressively hairsprayed ‘do and colorful, but dated, pantsuits.

In flashback, the young Garland (Darci Shaw) is slowly taken apart by producer Louis B. Mayer (Richard Cordery), who preys on her insecurity and denies her food and free time. It’s fairly well-known industry lore that would be seen as monstrous today, and it’s especially cutting when juxtaposed with the older, flailing Garland. She’s a walking emotional wound with caustic wit still intact: When a doctor asks if she takes anything for depression, she responds, “four husbands” with screwball timing.

An invitation to a residency at a London nightclub temporarily solves her housing and financial crisis. In the film’s most wrenching scene — and lord, there are many — she invites the only two men waiting outside her stage door to join her for dinner. They turn out to be a couple, and she ends up at their flat eating eggs. They couldn’t be there for her last show, they explain, as one had been jailed for “obscenity” (i.e. being gay).

No matter how well you know “Over the Rainbow,” you may never hear it as heartbreakingly performed as Zellweger sings it here. One hopes Garland would have appreciated this long-overdue indictment of the permanent damage done to her as a child actor, and the gratitude for the joy she brought to so many at the personal expense of just about everything.