MATTHEW Heineman presents us with three characters – ordinary men who do extraordinary things that the world needs to know about.

It all began with the Arab Spring, a yearning for freedom in Syria, controlled for forty years by the regime of President Assad. Three friends, student Aziz, teacher Mohamad and film editor Hamoud, began to document the civilian protests against Assad in their city of Raqqa.

In 2013, during the Syrian Civil War, militants overran government loyalists in the city. Western governments vacillated about getting involved in another Middle East conflict and so ISIS swept into the vacuum to announce the formation of a new Caliphate, with Raqqa as its capital. Savage killings, public beatings and beheadings were to follow.

"They painted our city black – shrouded it in darkness. We could not stand by and see Raqqa being slaughtered silently." So the loose affiliation of media activists gained a name and became organised in direct opposition to ISIS.

RBSS witnessed how ISIS was producing high-quality films and news reports and yet there was nothing in the Arab or international media to counter this propaganda. Facebook became the first tool of RBSS to amplify ordinary civilians’ voices, but after a journalist friend was apprehended, tortured and executed, leading to a string of further killings, the three friends knew they would have to flee their homeland.

Heineman allows the three main characters and their immediate family to tell their stories without interference. We feel their pain and loss, their isolation from Raqqa, exiled in Turkey, and fear for their friends and family left behind.

Just occasionally there are moments of levity as Mohamad is teased for his poor command of Arabic accents and grammar while writing news reports. "I was a Maths teacher!" he pleads in his defence.

While the media war intensifies, ISIS steps up attacks on RBSS, killing an associate in broad daylight in Turkey, and murdering Hamoud’s brother and father – dressing him in an orange jump-suit like the ones used by US forces in Guantanamo Bay. The exiled members show stoic bravery to continue their resistance from a new safehouse in Europe.

Despite bouts of negativity, RBSS appears to be winning the media war against ISIS, revealing the reality of life in Raqqa: food shortages, killings and the indoctrination of children, and as the violence inspired by ISIS overspills to France, Belgium, the US and Germany, RBSS goes global with interviews on mainstream TV and winning the International Press Freedom Award presented in New York.

Haras Rafiq, CEO of the counter-extremism think tank Quilliam, has said of City of Ghosts: "This very brave film dispels the propaganda that ISIS tried to propagate as a state which contains the land of milk and honey to entice would-be recruits. It shows them for what they really are: barbarians who rape and kill whilst the indigenous people lived in poverty and hunger."

I can only echo Haras’ words. City Of Ghosts is an important documentary. One has to congratulate Heineman for making this film and the support of renowned documentarian Alex Gibney as executive producer, but the real accolades must go to the unnamed citizen journalists on the ground in Raqqa and their three comrades in exile, bravely doing some of the most important work in the world.

Review by Dave Taylor

City Of Ghosts (18), 92 minutes, showing at City Screen, York, in the Discover Tuesdays documentary slot, Tuesday, September 5 at 6.20pm. Box office: picturehouses.com/cinema/York_Picturehouse or 0871 902 5726