Image copyright Studio Soho Image caption The film Undocument tells the story of four migrant families, focusing on how the children are affected

"When you see people dying in trucks and children dead on shores in the news - you can't ever imagine yourself in that situation," says filmmaker Kyla Simone Bruce.

Her film, Undocument, focuses on the children of four families wanting to live in a new country, caught up in the struggles that ensue.

Kyla, 33, starts from the premise that "nobody wants to leave their home or their family - it's out of necessity".

She thinks the current system is "tearing families apart", with people who are in a country illegally "stuck in detention centres" or worse.

Image copyright Kyla Simone Bruce Image caption Kyla Simone Bruce says traffickers often tell migrants to get rid of their personal documents

"There's a real misconception that people want to come here to sponge off the system," she says. "People migrate when you're pushed to the point that you have to provide for your family - or just to survive."

Recent news stories about migration have included grim revelations about the deaths of people trying illegally to enter new countries.

In October last year, 39 Vietnamese people were found dead in the back of a refrigerated lorry in Essex. Back in 2015, the photograph of a drowned young Syrian boy lying face down on a Turkish beach sparked an international outcry over the human cost of the migration crisis.

Kyla, while fully aware of the "shocking" deaths that can result, wanted to explore it from a UK perspective, spending three months observing at a London immigration court.

Keen to make the film "as real and truthful as possible", she also got a lawyer to double check the storylines' legal aspects.

"At the court you see that a lot of the people working there really want to help, and the strain that's put on them is what makes it all so difficult," she says, adding everyone has to navigate the "bureaucracy" and paperwork involved.

Image copyright Studio Soho Image caption A child is desperate to see his mother, in this detention centre scene

Kyla stresses Undocument was not political, however, saying "it was really important for us to kind of just show it how it is, and not finger-point or push it one way or the other, because I think that really turns people off ".

She made the movie with Iranian filmmaker Amin Bakhshian, and they finished it in 2017, before illegal immigration and detention centres "became such a relevant topic in the media".

Image copyright Amin Bakhshian Image caption Amin Bakhshian, who co-directed the film, grew up in wartime Iraq

"Obviously now everybody has their opinion and knows a lot more about it - back then I didn't know about the jungle in Calais for example, although that had been going on for years and years," she says.

She and Amin wrote the film together, having met as students at London Film School. His stories of migration, which he witnessed growing up during the war in Iran and Iraq, made them want to look at the lives behind the headlines.

"Amin could see why people were leaving during wartime," she says simply.

Image copyright Studio Soho Image caption The pregnant woman trying to join her husband in Undocument struggles to make the journey

Kyla hasn't seen him since they made the film as "it's so hard for him to get a visa to come here right now", so they haven't watched the finished product together.

Their film is split into four segments, with the first telling the story of a pregnant Afghan woman - married without her family's permission - trying to join her husband in the UK. The second focuses on an Iranian boy and his mother, trapped with other migrants in a house in Greece at the mercy of a trafficker meant to be helping them travel north.

But did she and Amin did wonder, given some of the global headlines about migrant deaths and illegal migration, if their film should have been more hard-hitting?

"I was worried about that," she says, but adds: "Our stories were shocking in their own way and we realised we were being true to ourselves in the storytelling, because we didn't want the shock value. And actually, that's what the news does."

Image copyright Studio Soho Image caption The boy in Undocument finds himself in a situation which both frightens and fascinates him

Their film shows how the migrants are powerless the second they hand control of their lives to the traffickers, who are total strangers.

Amin directed the first two segments of the film in Iran, basing both on true stories.

The first includes footage of migrants being hidden in lorries, nailed in behind wooden boards, while many of their suitcases are tossed outside the lorry as the traffickers cram in more and more people.

Freezing lorry conditions

"For people trying to come here - they pay so much money, so they're actually quite successful in order to have the means to get that much cash," says Kyla.

"They're sold a lie - they don't know how long they'll be in the lorry for, and they're suddenly put in this survival situation, whether they're just fighting for their lives. They don't realise they'll be trapped with no air and freezing conditions and you might die.

"You're in situations where you can't communicate, suddenly it's a different language and you're being passed through this network and your choices are taken away and you can't go back."

Image copyright Studio Soho Image caption One of Kyla's segments shows a family battling deportation due to lack of documents

She says often illegal migrants are told to get rid of their official documents because "in some countries it takes the power away if they can prove where you're from".

Kyla grew up in the UK, in Suffolk, but had a German mother so has always identified with feeling a bit different. Amin's childhood experiences of war meant he saw its impact first hand, as people fled for a better life elsewhere.

One of the tales Kyla tells is of a family living in London, where the woman's partner is visited unexpectedly by immigration officers as he doesn't have the correct documentation.

Her other film shows the system through the eyes of an Arabic interpreter in a migration centre, struggling as he sees a boy separated from his mother.

Image copyright Studio Soho Image caption This woman's unborn child is caught up in its mother's situation

One theme that struck both filmmakers was that fear "becomes a normality" for children and young people.

In Amin's second story, the boy ends up "almost identifying with the trafficker and idolising him, because he's got money and power".

They used unknown and first-time actors for their film, and were inspired by filmmakers such as Mike Leigh (the former chair of London Film School) and Ken Loach.

"We wanted to humanise the people going through those situations," says Kyla.

"We see news reports about numbers, facts and figures and deaths. It's then hard to see the individual human story, but without it, it's easier to turn a blind eye because you can't relate to it.

"But when you meet people, talk to them and hear their experiences, you find they're not really that dissimilar."

Undocument is released in select cinemas in the UK on Friday 31 January.

Follow us on Twitter @BBCNewsEnts and on Facebook. If you have a story suggestion email entertainment.news@bbc.co.uk.