Raqqa, the Syrian city at the heart of Matthew Heineman’s new film City of Ghosts, made headlines in early 2014 when ISIS forces invaded and declared it the “capital of the Islamic State.” In recent weeks, as City of Ghosts began a limited release in the United States, Raqqa returned to the front page. American-backed forces began pummeling the ISIS stronghold in early summer, and after its recent “victory” in the Iraqi city of Mosul, the US-led coalition has identified Raqqa as its “new number one” objective. The Western media have declared the fall of ISIS in Raqqa to be imminent.

Abdalaziz Alhamza, a Raqqa native and central figure in City of Ghosts, is less celebratory. “This year, the coalition forces have killed more civilians than ISIS in Raqqa,” Alhamza told a New York audience after a screening of the film on July 8. He’s also wary of what might follow the evacuation of ISIS. Extremism will never be eradicated by weapons alone, said the 25-year-old activist. “You can’t bomb an idea. This is a war of ideas.”

Waging this war has been Alhamza’s work since April 2014, when he and several colleagues founded Raqqa Is Being Slaughtered Silently (RBSS), a citizen-journalist collective dedicated to documenting the atrocities in their city. In the film, Alhamza recalls the arrival of the black-bannered ISIS convoys. By then, the residents of Raqqa had weathered an uprising and numerous clashes between warring militias—not to mention decades under the Assad regime—but these new occupiers, he says, were uniquely sinister.

“We quickly realized this group was unlike anything the world had seen before. They painted our city black and shrouded it in shadows,” Alhamza recalls in the film. ISIS quickly imposed draconian rules, banning smoking and forcing women to don veils and black shoes. Before long, ISIS staged its first public crucifixion. From that moment, violence proliferated, as ISIS transformed public squares into the sites of grisly executions.

 Horrified, Alhamza and his friends began capturing this violence on film and uploading it to social media. The act was reflexive, like a “scream,” he recalled. At the time, none of the members of RBSS had a background in journalism. Their aim was simple: to document and disseminate the horrors of life under ISIS in order to undermine jihadist propaganda and summon the concern of the outside world. Truth-telling, they reasoned, was the antidote to international indifference.

Heineman’s film employs this method, too. Much of City of Ghosts is composed of the stark footage gathered by RBSS’s guerrilla reporters. Decapitated bodies, bloodstained pavement, and bombed-out homes appear, and often linger, onscreen. The film also captures the deteriorating conditions of civilian life: uncollected garbage, a crumbling economy, and long lines of children waiting for rations of food and water. Highlighting these deprivations has been another pillar of RBSS’s mission, serving as a direct challenge to ISIS propaganda that touts Raqqa as an Islamic utopia.