A twisty and gut-wrenching drama, Lara Gallagher’s Clementine centers on a heartbroken Karen (Otmara Marrero), who breaks into her ex’s lake house and does what anyone would do after a breakup — obsessively listen to voicemails from her ex, get stoned, get drunk, and generally make bad choices (like the aforementioned break-in).

Another one of those bad choices is Lana, played by Sydney Sweeney (above, right), who Karen has an increasingly confusing and dangerous relationship with.

The relationship between the women is equally passionate, confounding, and tense. Sweeney instills Lara her with a mix of innocence and seduction, as she manipulates both Karen and the audience. The 21-year-old actress — who’s also appeared in Netflix’s Everything Sucks!, The Handmaid’s Tale, and Sharp Objects, working with powerhouses like Elisabeth Moss and Amy Adams — proves herself to be a star in Clementine.

EW chatted with Sweeney at the Tribeca Film Festival, where Clementine had its world premiere, about that movie, Amy Adams, and the cool projects she has in store for the rest of 2019 (including a small Quentin Tarantino film starring Leonardo DiCaprio and Brad Pitt called Once Upon a Time… in Hollywood, NBD).

ENTERTAINMENT WEEKLY: How did you get involved in Clementine?

SYDNEY SWEENEY: When I was filming Everything Sucks! in Portland, the producer knew the producers that were making the film and they sent him the script and he sent it to me and goes, ‘you should audition for this beautiful film.’ I read it on my phone and I went up to him. I’m like, ‘who can I get in front of to meet for this movie?’ And I went in and I auditioned and I ended up getting it.

What was it like working with Lara [Gallagher] and the filming process?

It was just effortless the whole time. I didn’t even feel like we were filming a film because we were on this beautiful location and everything was just so natural. Lara is an amazing writer and director and it was really fun working with her.

How did you build that relationship between Karen and Lana? It feels so fraught.

We just built it as we filmed because we did a lot of the scenes in the order they were supposed to grow. [Otmara]’s an amazing actress to work off of because she gives you so much without having to say it. I love working with an actress that you can just look at them and be able to react with your eyes and not have to do much else.

Speaking of other amazing actresses, you worked with Amy Adams on Sharp Objects…

Amazing. A dream. Every single adjective that describes incredible. Like how I was saying I like being able to work off an actor that you don’t have to say much, she’s very much like that. And Jean-Marc Valleé would just leave us in the room and we wouldn’t quite know where the camera was and he didn’t call cut and we were just going. And I love being able to do that with an actress, especially with Amy Adams.

You have a ton of great stuff coming up, what can you say about HBO’s Euphoria (about high schoolers dealing with drugs, sex, and violence) and the character you’re playing in it?

It definitely will show a whole new side of me. I think that a lot of people are going to be talking about this show. We take it to every single place that you think something should be taken. And then we cross every line that there is to be crossed.

You are also in Quentin Tarantino’s Once Upon A Time In Hollywood, which is one of the most anticipated movies of the summer.

It’s still very surreal. I need to see the film and be like, yeah, wow, I was in this?! That’s not me, come on!

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