Matthew Heineman’s documentary “City of Ghosts” has won this year’s Candescent award at the Sundance Film Festival.

The Candescent award was created by actress-producer Lilly Hartley in partnership with the Sundance Institute documentary film program. The award goes to a powerful social-issue film that has been supported during production by the DFP and premieres at the Sundance Film Festival.

Heineman, whose credits include the Academy Award-nominated “Cartel Land,” followed the journey of a handful of anonymous activists who banded together after their homeland was taken over by ISIS in 2014. “City of Ghosts” centers on a group of citizen journalists — dubbed “Raqqa is Being Slaughtered Silently” — as they face the realities of life undercover, on the run, and in exile, risking their lives to stand up against ISIS. Raqqa is an ISIS stronghold in Syria.

“City of Ghosts” premieres in the U.S. documentary competition on Saturday at the Sundance Film Festival.

“City of Ghosts had a profound impact on me,” Hartley said. “Matthew Heineman’s superb thriller of a documentary transformed my views and captured my heart. Raw humanity pulses at the core of ‘City of Ghosts.’ I am excited to support Heineman as he continues to make fantastic, fearless films.”

Hartley is an executive producer of “Trophy,” premiering at Sundance on Friday. She’s also a supporter of “Step,” which premieres on Saturday at the festival.

Candescent Films supports documentaries that illuminate social issues. Upcoming supported films include HBO’s “Solitary,” “The Departure” and Lauren Greenfield’s “Fantasy Island.”

Some of Hartley’s recent projects include “The Queen of Versailles”; “Sons of the Clouds,” starring Javier Bardem, for which she and Bardem won a Goya Award; “Who is Dayani Cristal?,” starring Gael Garcia Bernal; and “Likeness,” a short film starring Elle Fanning.

Past recipients of the Candescent award include: “How to Change The World,” “T(e)rror,” “Private Violence,” “E-Team,” “Gideon’s Army,” “After Tiller” and “Escape Fire.”