How to treat the scandal that rocked American figure skating in 1994, when Nancy Kerrigan was assaulted and her foremost competitor Tonya Harding charged with conspiring to remove her from the Olympic field? The answer, for screenwriter Steven Rogers and director Craig Gillespie, is to go a darkly satirical route, but retaining enough humanity to keep Harding from becoming a mere caricature (though those around here slip more fully into that category). “I, Tonya” takes a rather sordid episode and turns it into a film of goofy humor leavened with some serious drama and a touch of heart.

Presented in the form of a cracked documentary in which interviews with the actual players, recreated by the actors playing them, serve to segue into flashbacks, the story begins with Tonya at age three, taken by her harridan of a mother, chain-smoking waitress LaVona Golden (Allison Janney) , for a skating lesson. LaVona’s sheer force of will compels instructor Diane Rawlinson (Julianne Nicholson) to take the kid on, despite her misgivings, and LaVona, sensing a possible source of funds, pushes the girl (played in her younger years by Mckenna Grace, so good in “Gifted”) mercilessly.

By fifteen, when Margot Robbie takes over the role, Tonya has become a fearsomely strong skater, but her lower-class ways and flashy home-made costumes hardly endear her to the snooty skating establishment. But her mastery of moves that her competitors can’t match makes her an up-and-coming star despite attempts to undervalue her.

She also rebels, finally, against LaVona by falling for Jeff Gillooly (Sebastian Stan), a goofy underachiever with a penchant to resort to domestic violence as pronounced as LaVona’s was. They marry, but she leaves him after one row, only to be cajoled back. The suggestion is that she’s become so accustomed to bad treatment all around that she’s come to expect it—and maybe even come to believe that she deserves it.

It’s at this point that Kerrigan (Caitlin Carver) enters the picture in a major way, a friend turned rival—the princess who represents the face of the sport the establishment wants to present to the world. When “psychological warfare” emerges as a tool of the trade, Gillooly suggests to Tonya that they use the tool themselves, sending letters to Kerrigan that might undermine her confidence, and Jeff enlists his pal Shawn Eckhardt (Paul Walter Hauser) to do the deed. Eckhardt, a member of the Harding entourage who’s listed as a bodyguard, is in fact a nutball who, in his self-delusion, considers himself an international operator, and he ratchets up the operation to culminate in the knee-capping. But his execution of it is so inept that, as the Hard Copy producer played by Bobby Cannavale as one of the interviewees explains, it would have been beneath the Keystone Kops.

The upshot, of course, is that Harding is dragged into the investigation that follows, along with Gillooly and Eckhardt, and while she’s spared the prison terms they’ll serve, she’s banned from competitive skating forever; we see her move into the pro boxing ring, where her flair for the dramatic—and the penchant for violence that marked her life—seem right at home.

This tawdry tale kept the American public enthralled back in the day, and Gillespie and scripter have turned it into a rich parable about celebrity, sports marketing, class-consciousness and conspiratorial madness in modern American life, one that deftly blends comedy and tragedy. Gillespie has had a checkered career since he scored a modest triumph with the oddball Ryan Gosling starrer “Lars and the Real Girl” a decade ago—he’s tried all sorts of different genres without much success—but here he’s back on the quirky turf he seems to know well, and he balances the different tones skillfully.

He’s blessed with a terrific cast, headed by a breakthrough performance by Robbie, who manages to embody the mixture of toughness and vulnerability in Harding—and cut a convincing figure on the ice. Stan captures Gillooly’s combination of dimness and meanness too, but it’s Eckhardt’s deadpan portrayal of a guy living on illusions (and with his mother, no less) that seals the plot part of the plot. And looming over everything is Janney, who makes LaVona a stage mother from hell, a Mama Rose without the hint of a redeeming quality, even when her daughter seems to have fallen to the lowest possible point.

Jade Healy’s production design and Jennifer Johnson’s costumes are on period target, and cinematographer Nicolas Karakatsanis suggests the slightly seedy ambience of the tale, while joining with Gillespie and editor Tatiana S. Riegel to keep the film in constant motion; the skating sequences—which replicate, among other things, Harding’s jaw-dropping triple-axel jump (courtesy of some fine stunt work, of course)—come across as both authentic and exciting.

As one might expect, there remain questions about the details of how the whole Kerrigan business actually went down. But while Gillespie’s take on it might not be completely accurate, as cinema it scores high.