Before September’s Toronto Film Festival, almost nobody had heard of Lupita Nyong’o, the gorgeous Kenyan actress who hadn’t even graduated Yale Drama School when Steve McQueen gave her the most prominent female role in 12 Years a Slave. By the time the film screens at the New York Film Festival next week, though, everyone who cares about movies and awards season races would do well to learn her name.

The film is based on the autobiography of Solomon Northup (Chiwetel Ejiofor), a freeman kidnapped into slavery, and Nyong’o’s performance as Patsey, a young slave who’s become the object of obsession for sadistic cotton plantation Master Edwin Epps, played by Michael Fassbender, is easily one of the most arresting acting debuts in recent memory. Valued for her beauty and her astounding ability to pick 500 pounds of cotton a day — more than twice the haul of any male slave — Patsey is objectified by Epps, scorned by his wife (Sarah Paulson), subjected to horrifying cruelty by both, and often dreams of death as her release. Jada Yuan spoke to Nyong’o in Toronto about researching the role and the experience of getting whipped by Michael Fassbender.

You hadn’t even graduated from Yale Drama School before you got cast, correct?

Yeah, I actually got cast, I think, three weeks before I graduated.

It must have been crazy. You must have been so excited.

I was extremely excited and of course, extremely intimidated. I had impostor’s syndrome until the day I landed in Louisiana. I was certain that I was going to be fired. I was certain I was going to receive a call and they were going to say, “I’m sorry, we made a mistake.” Every single day. And it wasn’t until the day I was flying to Louisiana that they made the announcement on Deadline that Patsey had been cast. So the whole time I was like [whispers], “Maybe they’re reconsidering. They must be reconsidering.” Luckily, I wasn’t fired. [Laughs.] My friends can definitely attest to that.

What were the shooting conditions like?

Oh, it was the height of summer in Louisiana, so it was hot. It was extremely hot. And it was something else to be picking cotton in that kind of heat. And then I just recognized, these people were made of some strong stuff. The people who lived through slavery. I mean, they did that, picking cotton, more than sixteen hours a day, in that heat. A heat that was kind of challenging me in these kinds of plush conditions I was in. It was definitely very sobering, that experience. It was great to be there. Flanked by these oak trees that have been there for over 300 years.