THE screen image is both bewildering and haunting. Two young women are running across the bleak Highland gorse, breathing wildly, their faces showing absolute terror as they see a horseman, lifting his 18th-century rifle to his shoulder. Yet, this fearfulness is sharply contrasted with the gay tartan frocks billowing around them as they run.

The scene is featured in new film 1745, and we learn the young women are slaves on the run from their slave master. And if Scotland didn’t know – or choose to know – of its direct links to slavery in the 18th century (the country was at the very heart of the British slave trade for almost 200 years before it halted in 1833), it will now.

Directed by Gordon Napier and produced by John McKay, 1745 was developed by the Akandé sisters, Moyo, 29 and Morayo, 28, daughters of Nigerian immigrants who grew up in the Bearsden suburb of Glasgow.

The sisters both act in the film, alongside acting veteran Clive Russell (who plays Master Andrews) and Morayo has written the script, which won a place in the Scottish Film Shorts scheme last year.

She explains the genesis of the film. “I’d been researching Scotland’s history and I wanted to write a period drama about people of colour in Scotland because it’s something we don’t know very much about.

“In Glasgow's Mitchell Library, I came across a newspaper advert from 1745, which had been placed by the master of a runaway slave. The ad mentioned the girl’s name, Anne, described her dress and said she spoke some English.

“I was shocked that these ads were actually being run in 18th-century Scotland – the sort of ad people would run if their dog had run away.”

When Morayo had digested the information, she approached a group of historians who were working in conjunction with Glasgow University on runaway slaves in Britain: Dr Stephen Mullan, Nelson Mundell and Professor Simon Newman.

“I found them via Twitter actually,” she says, smiling. “And I found their research fascinating. They gave me a great insight.”

The writer, who has also studied drama in London and America, felt compelled to develop the story, fictionalising an account of two slaves, Rebecca Atkin (played by Morayo) and Emma Atkin (Moyo).

“It’s such an important story. I just felt it had to be told,” says Morayo.

The film's title has obvious historical import. "The reason we decided to call the film 1745 was because this was the most important year in Scottish history in regards to fighting for our freedom – the Jacobite rebellion," explains Moyo, who has been a model before turning to acting and has appeared in productions such as Macbeth at London's Globe Theatre. "That is what many Scots associate the year 1745 with.

"But what isn't mentioned in the history books or taught in the Scottish school curriculum is that there were also other people – people of colour – fighting for their freedom at the same time. This is what was fascinating about discovering the advertisements and also shocking.

“So when I saw Morayo's research, I jumped on board completely. I was so shocked to learn there were so many people of colour living in Scotland at that time.

“It was shocking to learn girls as young as three were taken from Africa and Virginia as young as possible to make sure they didn’t rebel against their circumstances. The slave owners did their best to try and normalise what they were doing to these young girls. It certainly wasn’t something I was taught at school.”

The likelihood is that many teachers would have known little about Scotland’s involvement in the slave trade, as part of Scottish merchants’ investment in the tobacco, cotton and sugar trade with America’s southern states and the West Indies. The second city of the Empire was to an extent built on the profits made from the use, and abuse, of slaves. But for too long this involvement was swept under the tartan carpet.

“I think there were around 100 slaves in Scotland at that time,” says Morayo. “It’s quite an incredible number. The slaves would have been taken from an African country and on to Virginia. That’s where the Scots traders would have bought them, to bring them back here.”

Slave owners, says Moyo, dressed their captives in their own image, treated them as they chose.

“Dressing the slaves up in elaborate clothing was a status thing, a way of showing their wealth and power. They would have to do laborious tasks and much more. They wouldn’t be running away if there weren’t mental anguish and physical abuse going on. The placement of ads was about these men not wanting to give up on their property, and to save face.”

What makes the film particularly poignant is the fact the Akandés' ancestors came from Nigeria (their father is a chemical engineer) one of the countries ravaged by slave traders in the 18th century.

Born in London, the Akandé sisters were tiny when they moved with their family to Pollok, Glasgow, where they suffered racial abuse. When they later moved to the more affluent suburb of Bearsden, they immediately felt accepted by the community.

Does the discovery of what the likes of Emma and Rebecca suffered impact on their perception of Scotland now? “No, we are sure of our feelings for Scotland, although it was a shock to learn of it because it was a different time,” says Morayo. “And it was a trading business. People were seen as cargo.”

“Yet, it’s not as if slavery had ended," adds Moyo. "It’s still happening in Scotland today with human trafficking. But it’s no longer about colour. However, making this film is a way of getting across to people what humans are still capable of.”

The story is also empowering. It focuses on the relationship between the two sisters but it also reveals what they are prepared to do to break free of the clutches of their owner.

Moyo expands: “The story of the relationship between the girls and their master is not black and white. It’s a very complex situation.”

Emma, we learn, has been sleeping with the master. Not from choice. She determines this is the only way to protect her younger sister from his advances. The self-sacrifice is almost the ultimate act. But it serves to remind us how vulnerable – and terrified – these young black female slaves would have been at the time.

“Rebecca doesn’t really understand the situation,” says Moyo. “She is thinking ‘Why would we even want to run away? We’re being fed, we have certain comforts and we’re not worse off that other people in Scotland.’ She feels if they run away they’re running off to an even worse situation. But what she doesn’t realise is the price her sister is having to pay. There lies the conflict with the sisters.”

Filmed on location last autumn at Gosford House, East Lothian, Glen Nevis, Glen Coe and Glen Etive in Lochaber, 1745 offers is a real sense of the isolation the women feel when they run away. It’s almost as if two astronauts have been abandoned on another planet, where the terrain in hostile and there is no hope of sustaining life.

“How are they going to blend into in the Highlands of Scotland, running around with their tartan dresses?” says Morayo?

As the young slaves are chased across the heather by their maniacal pursuer there are shades of the Revenant to be seen. There is cold terror in every scene. But there was also freezing cold water to endure as the pair ended up in a river. It’s fair to say this wasn’t a glamorous film shoot.

“Thankfully, we had a brilliant production team with us to make sure we didn’t suffer from hypothermia,” says Morayo, offering a grateful smile. “It was important to show what people would have endured. And we couldn’t avoid the reality. The girls would have had to swim rivers to escape.”

Clive Russell – best known for his roles in Outlander, Game Of Thrones and Ripper Street – offers the perfect performance of the pursuer, never becoming one-dimensional. His attachment to his slave women is nuanced. His deliberation over their fate intense.

“Clive was amazing,” says Moyo. “He offered us so much as an actor.”

What’s entirely obvious is the story of the runaway sisters has legs.

“We do have plans to work it into a feature film,” says Morayo. “But we’re still at the early stages.”

The film's producer. John McKay, describes "Scotland’s long involvement in slavery" as "an often forgotten secret of our nation’s history".

"Many of the fortunes made – and the elegant buildings we enjoy in our great cities – were built on the profits from forced labour of slaves captured in Africa and transported to the Americas and the West Indies," he adds. "And there were black people here too – brought back by their masters – their stories still preserved in 'Runaway Slave' advertisements. In a year when diversity in the cinema is on everyone’s mind, 1745 brings this shameful history to light, in a new and powerfully personal way.”

With the short movie due to be released in Scotland over the coming weeks, the Akandé sisters are working to make sure 1745 is seen at film festivals across Britain and indeed the world. If the Edinburgh Film Festival were not to screen this film it would more a shock than jumping into a freezing Scots loch in winter.

“We’ll have to wait and see,” says Moyo, her fingers crossed.

What’s certain is the Akandé sisters will continue to work together. Meantime, Moyo, at 29, is set to appear in a new American movie, Category Five, telling of criminals who hack into the US Treasury.

“I’ve also got a part in BBC’s Porridge,” she says. “But this experience of 1745 has been great. It’s about reflecting society on screen, but it’s also an exercise in creating your own work.”

Morayo, a year younger, will continue to write. “But I want to act as well as telling stories. The whole point is to make things happen.”

The sisters loved working on their joint film project but there is a moment they would rather not repeat. A scene calls for Emma to slap Rebecca on the face, an attempt to make her deal with reality.

What’s entirely obvious is that Moyo didn’t pull her punches when she hit her sister. It’s surprising their parents didn’t hear the slap in Bearsden, and that Morayo didn’t end up missing a couple of molars.

“Yes, it was real,” says Moyo, smiling. “But no, it wasn’t a payback for Morayo borrowing my jumper a few years ago. It was all about the truth of the scene. And it’s what my character would have done.”

Morayo accepted the reality of the scene outweighed her desire to avoid a skelped face. “But I was glad we managed to do it in one take,” she says grinning. “I didn’t fancy being belted like that again.”

A Scottish Film Talent Network Production in association with Compact Pictures and Larsen Films, 1745 will launch this summer