Peter Kosminsky on the need to humanise British Muslim jihadis in Channel 4 drama The State

The drama opens in 2015 as four British Muslims pack their bags and head for the Turkish-Syrian border. We meet Jalal (Sam Otto) who wants to follow in his brother's footsteps by fighting for Islamic State, and his best friend Ziyad (Ryan McKen). Then there's idealistic teenage extremist Ushna (Shavani Seth), as well as Shakira (Ony Uhiara), a skilled doctor and single mother who arrives with her nine-year-old son Isaac.

"I personally don't think we do any service to the people who've suffered at the hands of ISIS to pretend that the people who go over there are all clinically insane," writer and director Kosminsky explained at screening in London.

"It's easy and comfortable to say that, but unfortunately it's not true. If you try to look at a pattern of why people might go there, there are very few – they seem to come from all different socioeconomic backgrounds, all different levels of academic attainment."

"The one common factor seems to be a shallowness of their connection with their faith. So these people are either converts, recent converts to Islam, or people born Muslim but who've only – to use an associated phrase – been 'born again' relatively recently and come to an interest in their faith relatively recently. It seems from the research that the deeper your knowledge and understanding of Islam, the less likely you are to travel."

Kosminsky has a reputation for meticulously-researched dramas, and with The State he was taking no chances – bringing on board a crack team of researchers, all Muslims with relevant academic backgrounds. Before a single frame was filmed, this team spent 18 months building up a comprehensive picture of life for British jihadis and women in the Caliphate.

"The first thing was to try to make characters that were real, faithful to the research, and didn't allow us the 'easy out' of thinking that these people are all mad," Kosminsky said.

"The second thing, I'll be quite open about it, is that this is supposed to be a cautionary tale." That's why he had to make the characters believable: "Their attitude changes and I didn't think it was going to act as any kind of cautionary tale if you couldn't associate with the characters."

"I can't see that it helps to say that, 'Well don't worry because they're all horrible, mad, unsympathetic people.' The challenge for us as a society is that they're not quite that."

Each character's journey takes them in a different direction as they experience the realities of the Caliphate. The harrowing drama covers everything from rape to beheadings, public whippings, sex slaves, suicide bombings, murder, the repression of women, child soldiers, retribution and indoctrination. Some of our protagonists regret their decision to leave Britain – but some do not.

"What the research suggests so clearly was that one of the driving factors for people going was a sense of exclusion at home, and a sense of brotherhood and sisterhood when they got there," Kosminsky said – calling on viewers not to take the first episode at first value.

"Episode one ends with that almost sense of euphoria, of a band of brothers and sisters. It's misplaced, but a sense of purity, of having found a safe place. If we hadn't done that, it wouldn't have faithfully represented the research.

"The next three episodes are spent unpicking that view."

The State will air on Channel 4 on 20th August, followed by an international broadcast on National Geographic in September