In a season when women began telling their abuse stories en masse, Margot Robbie lands a perfectly timed triple-axel of a performance as Tonya Harding, famed figure-skater-turned-national-joke. Profane, darkly funny, violent and tragic, Craig Gillespie’s unconventional biopic chronicles the uber-American story of an Olympic competitor who shot to notoriety after being implicated in the 1994 kneecapping of her rival, Nancy Kerrigan.

It also gives long-lacking context to Harding’s rough-edged, awkward persona: a backdrop of relentless domestic violence.

Anyone old enough to remember the incident will be familiar with the major players: Harding, her mustachioed ex-husband, Jeff Gillooly (Sebastian Stan), and her dumb-as-rocks bodyguard, Shawn Eckhardt (Paul Walter Hauser). But unless you’re really well-versed in Harding lore, you probably won’t know the significance of another character: her abusive, hard-driving waitress mother LaVona, played by Allison Janney with both relish and chilling brutality.

The film, which says it’s based on true and “irony-free” interviews with all involved, cuts between documentary-style confessionals and standard biopic narrative. Janney nearly walks off with the film in LaVona’s current-day segments, perched on a couch with an oxygen tube in her nose, whiskey in hand and a parrot on her shoulder. Bobby Cannavale adds color as a sleazy “Hard Copy” reporter looking back on the tabloid story that just kept giving.

But nobody can pull focus from Robbie, an intense actress finally sinking her teeth into a meaty role as a woman who became, in her own wry acknowledgment, nothing more than a punch line.

“I, Tonya” is far from a deification of its subject, but it delivers a slam to the prim world of figure-skating for cold-shouldering Harding from the start. With her blue-collar upbringing and cheap, all-wrong costumes, she never fit the desired mold (as she’s told by a judge at one point). Behind the scenes, she went straight from being beaten by her mother to being beaten by her husband.

Gillespie walks a fine line in mining both the buffoonish nature of the crime and the deep sadness of Harding’s rise and fall, and mostly pulls it off. Is it disrespectful of him to point out comic elements (like the baton-wielding Kerrigan assailant who, faced with a locked door as he’s trying to escape, breaks the glass with his head instead of the baton) of a story that also includes sickening spousal abuse? I’d argue it would be less true to her scrappy spirit to reduce her to one-note victimhood. Mostly, I found myself hoping Harding — banned for life from the sport — gets as much of a thrill watching the dynamic skating sequences as audiences likely will.