Another World: Losing Our Children to Islamic State (Temporary Theatre, National Theatre)

Stories of young people leaving the west to fight with Islamic State are barely out of the news these days. But any meaningful information about who they are, and why they do it is hard to find. Verbatim playwright Gillian Slovo and director Nicholas Kent, have attempted to lay bare some of the truths behind the headlines and in Another World present the voices of some people affected by those who leave to join IS.

It's a varied 90 minutes, which at times becomes heavy with detail and at others shocks you to the core. The piece starts with a group of mothers in Brussels, each of whom have a son or daughter who has left for Syria. They talk in depth about the often bewildering chain of events that led to their children being recruited by IS. One is a not particularly devout single mother, another is a Belgian woman who has converted to Islam, another's son told her he was going on holiday to Morocco and never returned. Their verbatim dialogue all comes from interviews conducted by Slovo, who has partially edited them, and their stories are heart-breaking, shocking and confusing in equal measure.

Elsewhere we meet a researcher for the Study of Radicalisation, a man who knows first-hand what it is to be radicalised at a young age by an organisation like IS. There are students from Tower Hamlets, Moazzam Begg – the British Muslim once imprisoned at Bagram and Guantanamo who now campaigns against war on terror abuses – and Charles Farr the former director general of the office of security and counter terrorism. As with all Slovo's verbatim plays (The Riots, Guantanamo – Honor Bound to Defend Freedom) – and Kent's verbatim productions – the piece attempts to give as comprehensive a portrait as possible of an exceptionally complicated situation.

Kent's remarkable achievement in creating The Great Game in 2011 – a collection of plays at the Tricycle which focused on setting the political record straight on the past and present of Afghanistan – is not quite replicated with Another World. Where The Great Game broke big issues into digestible chunks, Another World is unwieldy. One of the catch-22s of the piece is that including background knowledge is vital, but the mass of information crammed into Another World lacks the drama to keep us interested. The facts, the figures, the first hand accounts drift into a bulk of words.

But the play does go some way to unveiling myths behind just how east and west got to this point. There are sections which pose the idea that Global Jihad actually began in the Cold War and that during this time America played a big part in encouraging extremist groups against the USSR. Listening to the mothers talk about their children, it is striking too, how Syria is like a steadily increasing black hole in which young men and women seem to disappear.

Kent keeps things simple with his production. Images, maps and news reports are projected onto several TV screens at the back of the stage and the strong ensemble of actors speak out to us, sometimes sitting, sometimes standing. He lets the interviews speak for themselves and from them one main message emerges: the danger of not paying attention. "I lived in another world" one of the mothers says, and though she thinks she's talking only for herself, there's resonance for us all, too.

Another World: Losing Our Children to Islamic State runs at the National Theatre until 7 May.