The ISIS-occupied Syrian city of Raqqa may be in the news this week, but for years one of the only sources of information about it came from a group of heroic citizen journalists. They call themselves Raqqa is Being Slaughtered Silently (or RBSS).

The documentary “City of Ghosts” is a profound study in bravery; these men not only continue to risk torture and death (ISIS threats followed them to Turkey and Germany), but spend most of their waking hours watching and posting atrocities filmed by the equally courageous resistance within Raqqa, where the slightest infractions are punishable by death.

You can’t unsee what you see in “City of Ghosts.” Director Matthew Heineman (“Cartel Land”) includes RBSS clips depicting executions, and I think it’s good to be prepared for that. But nothing you’re going to see comes close to what the people of Raqqa have actually endured.

The least we can do is watch what they’ve risked their lives to show us — and help break the silence. Their story should be required viewing for anyone engaging in discussion of the refugee “problem.”