A close-up view of horror in Syria

City of Ghosts tells the story of the men who are trying to inform the world about abuses in Raqqa.

Most journalists seldom -- if ever -- put their lives at risk. That statement can't be made about those brave souls who report for RBSS. You'll understand why I'm talking about danger as soon as I tell you that RBSS stands for Raqqa Is Being Slaughtered Silently, a group formed to chronicle the human-rights atrocities committed by ISIS in the devastated Syrian city of Raqqa.

Director Matt Heineman (Cartel Land) introduces us to some of the Syrians who work for RBSS in his painfully powerful documentary, City of Ghosts. Some members of RBSS work inside Raqqa and others have been forced to seek refuge in Turkey or Germany. RBSS's relocated journalists serve as the organization's dissemination arm. RBSS material has been used by major news organizations and also on the organization's Facebook page.

But leaving Syria doesn't guarantee security: ISIS has vowed to kill these impromptu journalists wherever they seek refuge. And in Germany, members of the group also have faced the antagonism of angry crowds that would like to see them deported.

To say that Heineman's film is difficult to watch understates the case. Using plenty of RBSS footage -- much of it shot with cell phones at great personal risk to the citizen photographers who wielded them -- we see point-blank murders and other horrors that will force many to turn away from the screen.

I've been calling the men who operate RBSS "journalists:" That's not exactly true -- at least they're not journalists by choice. A school teacher, for example, has found himself working for RBSS because of his convictions that his homeland must be liberated from ISIS terror.

And unlike most journalists, these citizen journalists are intimately connected to the stories they report. For example, Hamoud, a cameraman for RBSS, is shown watching images of his father being executed by an ISIS combatant. It's impossible not to think about what must be going through Hamoud's mind and equally impossible to know.

RBSS is not alone in using video. Heineman also shows how ISIS has become increasingly sophisticated in making propaganda and recruitment films.

You won't find a lot of background in City of Ghosts: ISIS moved into Syria after the Arab Spring set off civil conflict and destabilized the country. That's about it.

But a complete political picture of events in Syria isn't the point: RBSS's journalists are dedicated to making sure that the world knows what's happening in Raqqa and, by extension, so is Heineman. RBSS has taken away any opportunity for Westerners to say, "If only we had known."

I'm not sure whether City of Ghosts deserves to be called a great film, but it definitely should be seen. At a minimum, we owe the people of Raqqa our pledge not to look away from their suffering.