When the Islamic State tried to overwhelm Yazidi and Kurdish territory in northern Iraq, fighters met an unusual form of resistance: An all-female combat unitof Yazidi women who had been captives of the group.

French filmmaker Eva Husson’s “Girls of the Sun” is at once a gritty war movie and an interior drama of suffering and perseverance in conditions few of us could imagine. Told initially from the point of view of Mathilde (Emmanuelle Bercot), a French journalist embedded with the unit, the film’s focus smartly shifts to Bahar (Golshifteh Farahani),the French-educated battalion commander.

She’s pretty tough. After killing one Islamic State fighter in a skirmish, she hears his cell phone ring. She answers.

“Who is this? Where is my brother?” a voice asks.

“He’s dead,” Bahar says.

“No he’s in paradise,” the voice says.

“No, he’s in front of me, stone cold dead. And killed by a woman. Care to join him?”

Must have been devastating news to the dead fighter’s brother, because, as Bahar explains to Mathilde, “They think they won’t go to paradise if a woman kills them.”

The unit’s mission is not only to defeat the Islamic State, but also to liberate the women and children they have captured. One of them is Bahar’s son.

As in real wars of this kind, fighting only happens occasionally. Waiting is also a tactic of war, and much of “Girls of the Sun” explores the personal backstories of the protagonists and the unit’s interaction. Sometimes the movie is slow going, made slower by the lack of depth of the supporting characters in Bahar’s unit.

Mathilde, wearing a Marie Colvin-esque eye patch, isn’t really necessary to the movie; the story could have been told without her. You don’t get the sense of her doing any real reporting — she just seems along for the ride.

Still, “Girls of the Sun” has an air of authenticity and grit that’s convincing, and Farahani, an Iranian-born actress, makes us care.

M“Girls of the Sun”:Starring Golshifteh Farahani, Emmanuelle Bercot, Zübeyde Bulut. Directed by Eva Husson. In Kurd, French and Arabic with English subtitles. (Not rated.)Theaters and Showtimes