The strange-but-true origin story of I, Tonya involves star/producer Margot Robbie reading the script and praising the writer for having such a rich imagination.

Only later did she learn the story was true — that in 1994 one Olympic figure skater, Tonya Harding, become involved in a conspiracy to injure another, Nancy Kerrigan.

"When I found out it was a true story, I was even more intrigued. Because everyone had such a strong reaction to Tonya, and so many people clearly hated her. And I really wanted to know why. And that took me to larger issues — classism, people who are economically disenfranchised, the way that women are expected to conform to narrowly defined roles, the way women are pitted against each other. The script led to so many bigger conversations, and so much of it is extremely relevant today," said Robbie, whose production company, LuckyChap, made the picture.

I, Tonya charts Harding's rise from a poor girl living in Oregon, from a broken and abusive home — a trajectory made possible by her astonishing prowess at skating.

She is unable, however, to break the gravitational pull of her mother (Allison Janney), who was emotionally and physically abusive — traits shared by Tonya's husband (Sebastian Stan).

Depicting that domestic violence was Robbie's biggest challenge as an actor and producer. She hired the director (Craig Gillespie) who had the best ideas about how to make the scenes defensible, especially in the context of a movie with the tone of black comedy.

"It was Craig who said you can't sugarcoat it. That would be a great disservice to Tonya. You have to show it. Then he had this great idea to have Tonya speak directly to the camera. She's sort of like the audience's emotional guide through these scenes," Robbie said. "I think that makes it easier for the audience, even though the violence is hard to watch. But violence should be hard to watch. It's a tricky dance."

Also tricky — finding an actor who could play Tonya's husband, Jeff Gillooly. Someone who could somehow occupy the character and not alienate the audience completely. She looked at many actors until seeing something in Stan's audition that somehow made it work — as Stan puts it, showing the "funny, endearing" guy that Harding fell for, and the "scary" guy she had to leave.

"Margot 100 percent deserved a lot of the credit for making this work. It's amazing. She's very young to be doing what she's doing — so proactive about her career. I'm looking at her during the making of this movie and thinking …  I should start my own company," said Stan, better known as Bucky Barnes in the Captain America movies.

"You watch Margot, and you see she's very passionate about what she's doing. I think she's interested in stories that give women a voice. And I think she saw there was something in Tonya's story that had been overlooked."

Robbie met with Harding before filming (recently, they've been on the red carpet together) and was surprised by Harding's curiosity — Harding was 24 at the time of "the incident," and she wanted to know how Robbie was handling fame at such an early age.

Robbie said Harding is now quite happy, remarried with children, and doing well. Robbie commissioned a rewrite to show Harding as she is today but stuck with original ending, which shows Harding's post-skating career as a fighter, in keeping with the movie's theme.

I, Tonya also reminds people of Harding's phenomenal gifts as a skater. When Robbie went looking for a skater/stunt double to land the unprecedented double-toe-loop, triple axel that Harding first performed in 1991, the movie's skating coordinator said it would impossible.

"She said there's no one who can do it. Only six women in the world have done it since Tonya did it 25 years ago. It was insane what she did."