“The Stoning of Soraya M.” is a relentlessly grim and powerful movie with terrific acting and a sustained, horrific ending that’s not for the squeamish.

The film, based on a true story told by Paris-based Iranian journalist Freidoune Sahebjam in the 1994 best-seller of the same name, is a graphic depiction of the brutality of fundamentalist sharia law sanctioned in Iran and other Islamic countries, including U. S. ally Saudi Arabia.

Set in a village in southwestern Iran, the story surrounds Soraya Manutchehri (Mozhan Marno), a loving and brave mother of four whose brutal and unfaithful husband, Ali (Navid Negahban), wants to divorce her for a child-bride. She refuses his terms to split up, fearing she will be unable to provide for herself and her daughters. She also rejects the village mullah’s proposition to help support her by paying for sex.

The husband and mullah set out to find her guilty of adultery, easy enough to do under sharia law since the burden is on the woman to prove her innocence.

The film’s terrible outcome is telegraphed early on and feels relentlessly oppressive, making it hard at times to sit through. As a boy I first experienced that feeling in “Billy Budd,” when the virtuous sea merchant, played by an angelic Terence Stamp, is marked for death after striking and accidentally killing a sadistic officer.

His last words before being hung, “God Bless Captain Vere,” were a shattering indictment of the horrific miscarriage of justice and destruction of innocence.

So, too, is “The Stoning of Soraya M.,” although the treachery takes another form.

The acting is the film’s strongest suit, with a terrific performance by Shohreh Aghdashloo as Zahra, Soraya’s aunt who stands up to village authority as she tries in vain to save her niece. Zahra also risks her life by telling Soraya’s story the day after the stoning to a journalist (Jim Caviezel) whose car breaks down, adding another element of drama when he gets ready to leave.

There is poetic justice in Aghdashloo’s role, since she was forced to flee Iran after the Islamic Revolution, later earning an Academy Award nomination for the 2003 film, “House of Sand and Fog.”

Marno offers a powerful performance as the wife who maintains her dignity and grace while being defiant in the face of such cruelty and degradation.

In the gruesome, 10-minute-long death scene — preceded by a shot of little boys eagerly gathering stones to transport in their wheelbarrel — Marno bravely meets her fate. Buried to her waist, she is pummeled with rocks thrown by village vigilantes that include her own father, two young sons and husband, stopping and starting again after movement is found in one half-opened, blood-filled eye.

Director Cyrus Nowrasteh obviously wants the viewer to feel just how sickening the stoning of human beings is, given that it continues to this day. But “The Stoning of Soraya M.” goes well beyond what was necessary to convey that.

Still, the scene has a resonance that can’t be easily discarded. At last year’s Toronto International Film Festival, the movie was voted runner-up to “Slumdog Millionaire” for the audience choice award.

The scene also exposes the cartoonish caricatures the sheepish villagers present, with virtually no dissent among them.

“This is a man’s world,” the menacing Ali tells his sons as his wife and daughters avoid his gaze. “Never forget that, boys.”

THE STONING OF SORAYA M.

Three stars

STARRING: Shohreh

Aghdashloo, Mozhan Marno, Navid Negahban

DIRECTOR: Cyrus Nowrasteh

RUNNING TIME: 116 minutes

RATING: Not rated, but R equivalent for cruel and brutal violence, brief strong language. In Farsi, with English subtitles.

THE LOWDOWN: A husband falsely accuses his wife of adultery, a crime under sharia law punishable by death.