The State review: Peter Kosminsky's ISIS drama is uncomfortable but essential viewing

Meet Jalal (Sam Otto), who wants to follow in his "martyred" brother's footsteps, and his best friend Ziyad (Ryan McKen). Meet teenager Ushna (Shavani Seth), who dreams of a jihadi husband and hasn't told her mum where she's going. And meet Shakira (Ony Uhiara), a skilled doctor and a single mother to young Isaac.

Four Islamic extremists as the protagonists of the story? It's uncomfortable. That is, of course, a deliberate choice.

This is a nuanced drama, and Kosminsky has made the decision to humanise his characters instead of showing them simply as evil incarnate. One moment you will be sympathising with Shakira's outrage as she is told she cannot practise medicine because she is a woman, or that she must marry so she can have a male guardian – and the next moment you will remember that she was the one who knowingly walked away from a life in the West. One moment you will feel Jalal's horror as he is told to choose a Yezidi sex slave, and the next you will remember that this is the result of the regime he fights for – and that he continues to fight for.

Why are they here? Each of our Brits has a different reason: Shakira was responding to ISIS leader Abū Bakr al-Baghdadi's call for skilled workers, and wants to fulfil her dīn (divine purpose); Jalal is following his brother; Ziyad seems to be looking for adventure; Ushna says she wants to be a "lioness among the lions".

But because Kosminsky has made a decision to bring everyone to Raqqa within the first few minutes of the first episode and skip all the preamble, it's pretty hard to understand what has led each of them to this extremist interpretation of Islam and to their admiration of Islamic State. In some ways that works, and it must have been necessary to set limits on what could have become a very sprawling (and even more expensive) mini-series, But it is also frustrating.

How did the quartet become radicalised in the first place? At a press screening in London, Shavani Seth mentioned that she was given a proper backstory for Ushna who had been drawn into extremism by the internet, but you wouldn't know it from what you can see in the drama (even if you'd guess it from all the news stories about jihadi brides). And when it comes to doctor Shakira, it is especially hard to comprehend how she arrived at such an extreme decision.

Still, this is a narrative that unfolds piece by piece, giving glimpses of our characters' motives and true feelings as it goes. It's a brave approach: you really have to trust viewers to commit to the series and see where the story goes.

In fact, it's hard to emphasise that enough. Because we are experiencing the story from Ushna, Ziyad, Jalal and Shakira's perspective, the narrative arc means that episode one is very different from episode four. Anyone who watches only the first hour will come away with a strange impression, because the first instalment shows our young Brits having a great time: bonding with the lads, playing with guns, living with like-minded people, being congratulated for the strength of their commitment and faith.

But if you are going to watch The State, commit to watching it until the bitter conclusion.

"Episode one ends with that almost sense of euphoria, of a band of brothers and sisters," Kosminsky said at the screening. "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."

To give a sense of what he means by "unpicking", The State goes on to cover the realities of life under ISIS: persecution, repression of women's rights, polygamy, slavery, public beheadings, floggings, child soldiers, bombing, slaughter, rape, and Muslims killing other Muslims. Each character has their own reaction to these cruelties, and each ends up in a very different place by the end.

Is The State a violent drama? As the horrific list above suggests, there are plenty of moments that will shock viewers. But Kosminsky also made a decision not to show more than was necessary, and so we don't see any actual beheadings – only the knife at the neck, and afterwards the disembodied head. We don't see any rape, only the ISIS fighters selecting their sex slaves like cattle in the market place, and a room full of raped and murdered women covered in blankets. There is very little blood. You don't need blood to feel the gut-wrenching horror in each of these moments.

It's so grim that there is very little space for humour. But it is quite odd to see the Brits dropping slang in the middle of Syria. Ziyad: "I ain't never going back to that kuffar dump. So wagwan?" – or "Just chop a few necks and suddenly everyone bless." Occasionally the dialogue seems a little contrived, but most of the time it rings true.

What about the truth of the rest of the drama? While The State is a work of fiction, researchers did spend 18 months exhaustively compiling material to ensure it was as accurate as possible – creating a sort of composite picture of real life. Anonymous interviews, evidence from social media, news stories, first-hand written accounts: everything went into the mix.

Out of this, a few key character types emerged (siblings following siblings, best friends going together, young girls radicalised on the internet, skilled workers responding to the call) and so Kosminsky created Jalal, Ziyad, Ushna and Shakira. Any time a storyline seems implausible, look into it: something similar – or worse – probably happened in real life.

The bottom line? The State is a hard watch, but a stunning piece of drama. Watch it all.

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