The 28-year-old actor filmed her scenes as Sara in the feature debut from Danish documentary filmmaker Jeppe Ronde in 2015 but the movie is now getting a DVD release in the UK.
The movie follows Murray's character who moves to the former mining town of Bridgend with her policeman father (Steven Waddington).
She discovers that the town has been plagued by a string of suicides and as Sara is drawn into the clique of teenagers who hang out together she realises what is causing the deaths.
"It was physically and emotionally the toughest job I've ever done. It was a joke how many bruises I had on my body every day. I'd go into costume and makeup every morning and go 'look at me!' because my arms were covered in bruises. It's because you want everything to be real," she said.
"That was the other thing with Jeppe from day one: we're not going to fake anything. It's got to feel real and it's got to feel true.