In 1997, a fourteen-year-old girl was walking home from school when men on horseback and armed with whips surrounded her. They dragged her—terrified, confused, screaming, and fighting—onto one of the horses and rode to the edge of the village. They threw the girl in a shed and locked the door. Not long after, a man entered the shed. He beat and then raped her. He announced that she was going to be his wife. When the girl saw a chance to escape the next day—the men had left the shed door unlocked, and a rifle lying next to the door—she took the weapon and ran. When the men caught up to her, she shot her would-be husband in self-defense.

Seventeen years later, in 2014, another fourteen-year-old girl was living with her husband, whom she had recently been forced to marry, when she prepared food for him partly made of rat poison. He and three of his friends died after eating the meal. The second incident took place in northern Nigeria. The first happened in southern Ethiopia, and is the subject of the 2014 film “Difret”—a thoughtful, if at times heavy-handed, treatment of the abduction, slaying, and ensuing trial. The film is now touring the United States. It’s a “message movie,” one that convincingly rails against the widespread problem of child marriage while raising the question of how effective a message movie can be.

“Difret” opens with the startling and disturbing kidnapping, moving abruptly from idyllic fields, where a teen-age girl named Hirut is playing, to the marauding horsemen who appear out of nowhere. The film’s initial scenes are bare; the film does not waste frames as it takes us to the aftermath of the killing, with Hirut in jail and awaiting trial and a likely death sentence. As in real life, a lawyer named Meaza Ashenafi (played well by Meron Getnet), the founder of the Ethiopian Women Lawyers Association in Addis Ababa, comes to Hirut’s defense, determined to force the courts to protect a child who was not only taken against her will but threatened with death.

The outlook was dim: a prior judgment in Ethiopian courts had forced a pregnant girl to stay with her captor, and no woman had ever been awarded a self-defense ruling. We watch Ashenafi navigate the maze of courts and traditional councils, allied in their patriarchy and sexism, all the while growing more desperate and reckless. Out of jail on bail, Hirut faces the revenge-seeking relatives of the man she killed. “Difret” (which can mean “courage” or “rape” in Amharic) excels at capturing the mind-numbing, bang-your-head-against-the-wall bureaucracy of much of sub-Saharan Africa, and at showing the cultural context of a place where bride kidnapping is not so strange or rare.

After the real trial ended, Ethiopia eventually passed legislation, in 2004, that made abduction and rape punishable by a sentence of up to fifteen years, though enforcement is still inconsistent. According to the film’s director and writer Zeresenay Mehari, telefa, the practice of abduction into marriage, is one of the oldest traditions in the country and affects more than forty per cent of adolescent girls. Angelina Jolie said that she signed on as executive producer because the film “gives hope … for other countries where countless girls grow up without the protection of laws that shield them and their bodies, shows how the courage of brave individuals can awaken the conscience of a society.”

“Difret,”and the activist sensibility behind it (the film’s producers have started a petition against child marriage), reminded me of “Desert Flower” and “Blood Diamond,” two movies that tried to build entertainment upon Africa-related causes but had far less cinematic value. “Desert Flower” is the life story of the Somali model Waris Dirie, honing in on her experience of genital mutilation as a girl and her later turn as both a supermodel and activist against what some euphemistically call “female circumcision.” The film was uneven at best, with forgettable acting and storylines, but its portrayal of Dirie’s early life in Somalia was startling and moving. Similarly, in “Blood Diamond,” the cartoonish quality of the gunrunner and journalist protagonists was offset, at times, by the tragedy of Djimon Hounsou’s Sierra Leonean fisherman, who gets caught up in the conflict-diamond trade.

The line between art and message is a delicate one to tread, and films like these tend to fall clumsily on the side of the maudlin and oversimplified. Impressively, “Difret” ends on a note of ambiguity and uncertainty, but many message films reduce complexity to clear sides of good and evil, topped off with a hasty, tidy ending. When these movies are playing in festivals or theatrical release, filmmakers and actors will speak solemnly, if unsurely, about the cause in interviews, and, for a fleeting moment, “awareness” of the issue will be raised in the public consciousness.

But because most of these films are targeted at an international audience, which is already saddled with its own preconceptions of Africa, well-meaning message movies can ring false. Why tie the film so explicitly to a cause that “needs immediate attention,” whether through the plotting or promotion, if not to profit on the outdated idea of that there is a foreign land that needs saving?

Art can certainly dramatize real-life events, as long as it understands them, but it can’t be the earnest volunteer on the street with a Greenpeace clipboard. This kind of art is not really believable, for one, and it can’t match the power of local action, and shouldn’t try to. After the Nigerian girl was jailed for killing her husband, protesters wrote letters to the state government in Kano, where the girl was being held. Since 2013, other activists have held mass rallies and staged social-media campaigns against child marriage throughout Nigeria, where, in several states, girls under eighteen can wed. Something worked. Earlier this year, a court ruled that the teen-ager could go free.