Pretty Little Liars star Ian Harding and Harry Potter’s Evanna Lynch are getting steamy in the bedroom.

In the indie crime thriller Addiction: A ‘60s Love Story, Harding plays Max, a young man in the ‘60s who decides to quit college and meets the love of his life, Theresa (Lynch). It’s then that his life begins to spiral out of control, as he becomes a heroin addict who gets tangled in the corrupt and dangerous underground porn industry.

WATCH: Ian Harding Is Seduced by Drugs and Porn in First ‘Addiction’ Trailer

“Working on Addiction and playing Theresa, I was very aware that I was telling a real person’s story and it meant a great deal to a lot of people – the stakes felt uncomfortably high,” Lynch exclusively tells ETonline.

The 24-year-old Irish actress admitted there were aspects to Theresa that felt “alien” to her – including marrying young, childbirth, raising children, being a New Jersey native and having a “junkie husband.” The tight production schedule only made it more “nerve-wracking,” she recalls.

“But I think that being that far out of my comfort zone taught me to rely on my gut as an actor. There were days – the labor scene springs to mind – where it was just me and my imagination and I had to trust there was unlimited scope there if I could let go of trying,” she adds.

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In a scene from the movie, which ETonline exclusively debuts, Max and Theresa have just begun dating and Max has yet to tell his family that he’s quit college or that he’s starting a serious relationship. Just as he’s about to get caught in a compromising position, Theresa sneaks out through his window – but Max’s problems are only about to get worse.

“That was the most exciting part about Addiction,” Lynch says, “being in entirely uncomfortable situations and realizing I didn’t need permission or experience or prior knowledge to get lost in them.”

The film marks Tate Steinsiek’s feature directorial debut and was co-written by Max Bornstein and Jason Noto. Carol Kane, Brendan Sexton III, Leo Fitzpatrick, Chaske Spencer and Polly Draper co-star.

Addiction: A ‘60s Love Story is available on iTunes, VOD and DVD now, and premieres in New York City’s Cinema Village on Friday.

Hit play to watch the trailer for the movie below.