If the action in A24’s latest offering Waves was to follow the action of water, it would start like a seismic and stressful hurtling – an irreversible riptide forcefully pushing its characters underwater. The second half ripples out gently, heavy with the consequences and fallout of the first.

Directed by Trey Edward Shults, Waves sees Sterling K. Brown, Renée Elise Goldsberry, Kelvin Harrison Jr. and Taylor Russell as an everyday middle class family in America, left to pick up the pieces after a disturbing trauma shatters their seemingly perfect lives.

We caught up with breakout star Taylor Russell about using dreams to inform her acting, singing to Frank Ocean, and the message of forgiveness…

Tell us how you first got involved with Waves?
I had a mutual friend with Kelvin [Harrison Jr.] and he was on Facetime with him, and I jumped onto it and Kelvin said ‘oh we’re doing this move called Waves and you could play my sister’ and I was just kind of like ‘yeah, whatever’. That night when I went home I had an email in my inbox from my agent for Waves and it didn’t have anything to do with Kelvin; it was kind of like a serendipitous moment. From there I sent them a self-tape which they responded to, Trey [director, Trey Edward Shults] Facetimed me a week later, we had a good talk and then I met up with Kelvin and Lucas in LA, and we hung out for one night and then we kept on hanging out and then I got the part!

What drew you to the character?
It was one of those rare moments when you get a script and the words are words that you yourself would say, and it just feels so you. It just felt like ‘I am this person’, so I really got it.

Was there anything that you used to inform your acting process?
I used Dreamwork for my process in acting – it’s basically like going off dreams and writing them down while doing your work. Every single night that I shot Waves I was having nightmares, I’d wake up crying and screaming from them – it was just really, really intense and a lot of the moments in the movies came from scenarios from which I’ve dreamed up.

You and Kelvin had amazing chemistry as brother and sister – how did that come about?
I think we naturally fell into the brother and sister thing right away. We’re born five days apart in real life, so we have a lot of commonalities and we have a very similar sense of humour and we bicker and fight like siblings do, and kind of pick on each other and support each other and I don’t know it’s just one of those things where you meet somebody and you either really click or you don’t, and we really clicked in that way. I think we both just really wanted to be a part of each other’s lives and create that connection so it felt effortless.

At the heart of the film is this fraught family dynamic, and it focuses on a middle class black family which kind of feels like unprecedented for films that are coming out recently like why did you think it was really important to this discourse, like the film itself?

I think the message of forgiveness especially when something traumatic and awful happens, it’s such a strong one right now. It’s really hard and painful to open your heart up and forgive. It’s actually really easy in many ways to hold on. That’s important, but also I think that you don’t get to see black families, like middle class families who are quite normal and who do have many advantages in society except for you know the disadvantage in many ways of being a black person.

The scene that felt really profound to me is where you and Kelvin are embracing in the bathroom. It’s quite an upsetting scene…
You know, that’s one of the scenes that didn’t feel big at all at first, but it was super emotional because Kelvin was so emotional, and I was taken aback by that. He came in through a different entrance to the bathroom so I didn’t see him before the scene, and I was really taken aback by his level of intensity.

It must feel more natural that way, because you have no preconceptions of what’s going to happen?

Yeah, yeah, yeah. And then the way that it was used in the film, Trey blew my mind that it wasn’t in the script, but the way that he edited it. It was just so powerful and I really loved it, I loved seeing them together as brother and sister in that way.

What was your favourite scene to film?

I had this fantastic time creating a scene with Alexa, it’s in the middle of the film in the bathroom.

I love that scene!
Me too! I just love seeing two girls together, and Alexa and I didn’t have a scene in the script together at first. It wasn’t in there and we had watched the movie Persona by Ingmar Bergman and we found love with the two characters in that movie, and we were like we need a moment, like a Persona moment just between two girls. We asked Trey if he could put one into the script and him being the guy he is, he created the moment for us. It’s one of my favourite scenes.

The soundtrack is amazing – how integral do you think it is to the film itself?

Trey, you feel his voice very strongly, and music is one of those aspects of it and I don’t think it would be the same film if it didn’t have the soundtrack. It’s so pivotal and all of the music that you see in the film initially is in the script like Radiohead, Frank Ocean, Kanye West, Solange, all of it was in there and I thought if this guy can get all this music it’s going be the most epic thing ever. I mean even if it’s just singing along with Frank Ocean on a car ride.

Waves in out in cinemas on 17 January.