The political and social tensions of Scotland's potential independence are to be made gorily manifest on screen this autumn, in White Settlers, a horror movie in which a relocated English couple get terrorised by their new Scottish neighbours.

The central characters, Ed and Sarah, move away from London to the Borders, but on their first night are faced by masked locals; the film's tagline is 'They don't belong here...' Its release just before the Scottish referendum on independence in September means it could be cathartic viewing for Scottish nationalists; 'No' voters will meanwhile see their fears dialled up to an enjoyably cartoonish degree.

"It's not a political film; primarily, it's a suspense thriller, it's more like a horror film," the director Simeon Halligan told The Scotsman. "But the background to why it's going on has a political context." He said the timing of the release of the film, which was written some years ago, was a "happy coincidence".

The film's title is a reference to a term used by hardcore Scottish nationalists who formed groups like Settler Watch in the 1990s, to lobby against an influx of English immigrants. The film's Scottish writer, Ian Fenton, saw this resistance when he considered buying a house in the Borders region in 2003: "I started looking in the area. I was at a wedding of a relation of mine, and he said that they were having to rent a place to live because they could not afford to buy anywhere because people like me, we were buying up all the cheap housing around there. I thought I was on both sides of that camp as I could totally understand where this guy was coming from."

Halligan added that the film was about tolerance from both sides of the border. "There is a sense that there is an intolerance or a lack of understanding from both sides," he said. "So it isn't totally one-sided. There is a sense that the English in the story, whether consciously or unconsciously, are taking the Scottish for granted and the characters for granted. They take things that have been there for many years and don't think twice about it."

White Settlers is premiered at London's Fright Fest horror movie festival on 23 August, and goes on wider release in September.

This article was amended to reflect that Ian Fenton is Scottish, not English.