When Anya Taylor-Joy first read the script for Thoroughbreds, she knew she had to play the lead role of Lily in the film written and directed by Corey Finley. "I heard Lily so, so clearly," Taylor-Joy says. "It was clear Corey and I wanted to make the same movie." Shot in a Massachusetts suburb in just 22 days, the comedic thriller follows Lily, a straight-A student who reconnects with her childhood friend Amanda (Olivia Cooke) when her mother hires Lily to tutor her. "They have this toxic, bizarre female friendship," Joy says of the characters, who start plotting the death of Lily's overly harsh stepfather. The film also stars the late Anton Yelchin, who, in his final performance, plays a drug dealer in his late 20s. Here, Taylor-Joy talks about her offscreen chemistry with her costars, and how she prepped for her darkest role yet.

Anya Taylor-Joy and Olivia Cooke in Thoroughbreds.

Claire Folger

How did you end up signing on for this role?
It was the first script where I immediately called my agent and was like, "How do I meet [the director]?" I was desperate to be part of the project. I knew Olivia was attached, but I didn't know to which character. I only had eyes for Lily. After that, Corey and I met up for coffee and really vibed, and it came together really quickly. A day after I finished Barry, I started shooting Thoroughbreds.

What about Lily spoke to you immediately?
I think I'm very instinctive about my characters. When I hear their voice, or when I feel I belong to them or they belong to me, it's a kind of a tangible feeling. From a performance point of view, I was very intrigued by the idea of having to work from the outside in, rather than the inside out. When you first meet Lily, she is this very pristine, porcelain individual who is presenting a front to the world. She is trying to achieve this Instagram-level of perfection that isn't real. So I was really intrigued by the idea of presenting people with this very well put together facade, but as the movie went on, stripping away the moral insulation levels and seeing the messy, chaotic, raging person beneath.

Does Instagram-level perfection annoy you?
Instagram in its best light is a fun way of keeping up with your friends and expressing yourself. In a negative way, it's presenting the best version of yourself at all times that only needs to exist within a 30-second clip or image. So it doesn't show you a real person who has ups and downs. Especially in regard to Lily—she's so angry she can't achieve that. She can't be as perfect as these images. It breeds a really horrible sense of insecurity that can drive her to do some pretty dark things and harbor dark feelings within.

Have you ever played a character as dark as her before?
No, most of my characters, despite having a lot going on underneath, have been reacting to external circumstances. While I think Lily, not only is she a product of this Instagram society and extreme wealth, she's just reacting to her darker urges and how the urges are manifesting. And having that kernel of evil within you, growing, festering, it was something I was intrigued by as a performer. My characters are real people for me, so as we were shooting the movie I was defending Lily the whole time. When crew members were like, "God, she's such a bitch," I'd be like, "No! You have no idea where she's coming from, you don't understand. She's completely justified." It was only after filming finished and I started leaving her behind that I realized I'd been inhabiting a very toxic skin for a month.

As the twisted teen Lily.

Claire Folger

In what ways did you inhabit her? Did you start making Lily-like choices on set and in real life?
I'm so glad I'm not a method actor, but even so, I firmly subscribe to the idea that while I'm still always Anya, I'm living with Lily for that month. Certain personality traits will come through. With every character I play, it's like having a different roommate for a time, I adapt to allow her to fit inside myself. For Lily, that meant that for my friends and family I dropped off the face of the earth because Lily does not have a support network. To be able to inhabit that skin every day, I felt like I couldn't have my own support group taking care of me. I didn't want people to see me when I was "with" Lily.

It's like if you come home and your best friend is crying on the couch, and they're not your feelings, but your heart is breaking because you're seeing someone you love in pain. That's where I approach it from, character-wise. I guess it's not quite a stable way to live [Laughs]. I feel for my characters. By the end of the movie, I'm scared of Lily. My imagination has always been overactive, so I'm happy there's a job where that's actually useful.

Was that very intense for you?
It was so fast and intense, and it mostly takes place in that one house. During filming we lived three minutes away from it, so the shooting experience mirrored the intensity of what these two young women were going through. The two of them have been estranged for a while. Then they become obsessed with each other in a short intense period of time, and we shot it in a short period of time, so that added something to it. But Liv and I had to treat each other really kindly on set, because Amanda and Lily have such a bizarre toxic, obsessive, almost tender relationship. We had to be very kind to each other and respect each other's processes. I don't think we could have survived the movie if we were Lily and Amanda the whole time.

Did you know Olivia before working with her?
Even though we hadn't physically met each other, we were both at Sundance the same year. We were peripherally aware of each other, so it made it all the more special to be able to return to Sundance together for this film. I've been lucky to have incredible chemistry with a lot of actors, but with Olivia it was something on a different level, it was almost like we were completely physically, mentally, and emotionally aware of each other at all times from the first time we met. I would tuck my hair behind my left ear, and she would be doing the exact same thing. By the end of the first shooting day we became symbiotic, almost. It was this bizarre energy. We were always coiled around each other. Two years later it hasn't really gone away, we still move in tandem. I believe things happen for a reason, and I think there was a reason it was Olivia and I who did this film together.

Is there any special memory from set that you two share?
We were shooting a scene in the wine cellar together very late at night, and at around 2 a.m., for some inexplicable reason, the door to the cellar locked and we couldn't open it or continue doing the scene. So eventually we had to wake up the one locksmith, at 4 o'clock in the morning, to come and open the door so we could finish the scene. That was an intense moment. Another thing is there is this swing set behind the house. When things were getting emotionally difficult, I would just go out and swing. There was one time when I was dressed in all white, and it was really dark, I was swinging and Olivia thought I was a ghost. She was standing there scared, and I totally f---ed with her for a while.

With the late Anton Yelchin, in his final role.

Claire Folger

What was it like working with Anton?
What I keep saying is that it's difficult to talk about him as a person because he's my friend and I miss him and it's hard. Going on a press tour and having strangers talk about someone you love so much is a difficult thing to experience. But what's been beautiful about this experience is that it's not difficult to talk about him as a performer because he is so incredible. He has an ability to pick weird, quirky characters and imbue them with so much heart that you're rooting for them. He has a truly beautiful soul. It's been incredible to tour this movie around the country and see how unanimously loved and missed he is. In this film he took a character who, on the page, could have been quite a minor character in the hands of a lesser actor. And instead, Anton's character is arguably the moral compass of our movie. He's playing an older man who has had sexual relations with girls who were too young, so the fact that he manages to get you to root for him and think he is the best person in the movie… it's all him, man. The movie is wonderful, I think he would be proud.

On such a quick shoot with loaded days, how would you guys unwind after set each day?
The cast and crew did a lot of karaoke in Cohasset. Despite the fact that it is so charged, Corey made an interesting point: Apparently on comedy sets people are more brisk with one another because the subject matter is light, but with darker films people are more gentle and kind to one another because you're going to dark places and are emotionally vulnerable. So it was being cognizant of the fact that we were touching very dark subject matter, and everyone wanted to take care of one another. I'm Latin, I like hugs, so with every movie I've ever done, I start off giving hugs to everyone. Indefinite hugs.