Sundance-bound director talks about the unusual method he used with the actors of his scarier-than-expected psychological thriller.

For his feature debut In Fear, UK director Jeremy Lovering not only worried about scaring the audience, he also wanted to scare his cast. To convey a sense of actual fear, he didn’t let his actors (Iain de Caestecker and Alice Englert) know how the film’s story would end, so their surprised and fearful responses were more authentic. “The cast had to be in a position where things were unknown, then they would be in that state of fear,” says the writer/director, who talked through guidelines for every scene and then allowed for improvisation.

The story follows a young couple who get lost driving in a maze of country roads one night, and the four-week shoot was mostly at night in dark forests around Bodmin Moor.

Lovering says he asked himself: “How you can get as close as possible to authenticity?”

“I wanted to see if I could put them in a position to have them experience the story,” he notes. “It’s not strictly improvisation, there were guidelines and discussions.”

He knew the approach was risky, especially given how tight genre scripts usually are. “What I was excited by that it was a genre film that had to have certain genre beats, and at the same time the actors could have the freedom as characters to explore their actions and their emotional responses. It’s an unusual technique to apply to genre. You could apply it [more easily] to a drama about relationship, it’s a bunch of people sitting in a house and they’re talking and analysing.”

Lovering, is a former Screen International Star of Tomorrow, previously worked on shorts and on TV shows including Teachers, MI5 and TV one-offs including Money, and Miss Austen Regrets, plus docs such as Killing Hitler. He was inspired to write the story by a past trip to Ireland, where locals had put up misleading road signs that left him lost and confronting his own fear.

He cast relative newcomers Iain De Caestecker (BBC3’s The Fades) and Alice Englert  (Ginger And Rosa) in the lead roles, alongside Allen Leech (Tom Branson in Downton Abbey). They beat off stiff competition from lots of young talents who were eager to explore new ways of working. “There’s a lot of people who are 18-25 who are massively talented and very keen on this technique. It’s an actors’ dream. We saw a lot of people, there were a lot of people up for it.”

Both actors worked on backstories for their characters that aren’t seen on film but helped them with the psychology of the characters. “They worked together really well,” Lovering adds. “I couldn’t have made the film with a cast that didn’t buy into it.”

He did write a script, which he says was more like a first draft than a polished script. He sometimes gave the actors different pages of dialogue, or differing emotional instructions, for the same scene. His cunning plans worked: “The performances are very real, you totally believe this is potentially happening,” he says of the finished film.

Sundance programmer John Nein agrees, and he wrote of the film: “Though propelled by visceral thrills, the film transcends genre and offers a study in fear itself, creating a cerebral fable in which fear—of the dark, of the unknown, of ourselves—governs our nature, compels our choices, and may well seal Tom and Lucy’s fate.”

Nira Park and James Biddle produce for Big Talk with partners in StudioCanal (which also handles sales) and Film4. One week of the shoot was shooting daylight and dusk, with three further weeks of night shoots; Lovering adds that he loved the “elemental” vibe of shooting when it was “muddy, rainy and miserable.”

The film was shot digitally using an ARRI Alexa, Canon 5D and a GoPro, which allowed freedom during the shoot.

DoP David Katznelson did do some lighting work to keep the shots from looking too same-y in the dark. “We had variety even though we weren’t lighting it heavily,” Lovering adds.

They came up with an avalanche of material – he estimates it was nearly 50 hours of footage. “It was a complete nightmare,” he says of the edit. “It wasn’t simple because we never had the script to return to. It was like doing a jigsaw puzzle without a picture on the box.” (Jonathan Amos edited.)

The scares are more psychological than bloody – which makes sense given that Lovering’s favourite films include Repulsion, Deliverance and The Vanishing. “What I want to make anything that is a great script with a lot of layers and still approaches a genre,” he says. “I like the thrills without the gore.”

He says the film turned out to be more frightening than even he anticipated. “I think it targets primal fears. And it does it in a very ambiguous way. Ultimately you’re not sure where you are and what’s going on. It’s fear of the unknown, that’s why it’s scary.”

Lovering says In Fear, which doesn’t tick easy genre boxes,  seems like a good fit for Sundance. “It’s a festival I really love, and it’s always a validation when you get accepted to a festival like this.”

In Fear premieres Jan 20 in Sundance’s Midnight programme.