Most of us know gay conversion therapy is a hoax that preys on the fears of gay people and their families, especially those whose religion rejects non-traditional sexual orientations. What most of us don’t know—unless we’ve been unlucky enough to go through it—is just how this therapy attempts to bring about its unlikely transformation.

One person who does know is Gerrard Conley, whose parents pushed him into conversion therapy and who subsequently wrote Boy Erased, a memoir about his experience. The book has been brought to the big screen in a tale that is both harrowing and illuminating.

Directed by Joel Edgerton, who also wrote the screenplay and portrays a key supporting character, the flick begins by spelling out the dilemma faced by its teenage protagonist.

Jared Eamons (Lucas Hedges) is the son of a Baptist preacher in a conservative Arkansas community. In an early scene, the Rev. Marshall Eamons (Russell Crowe) stops in the middle of a sermon to ask those who are imperfect to raise their hands. Of course, everyone does, but Jared seems to ponder the question before joining in. Maybe he’s already worried about the troubling thoughts he has hidden from others and barely acknowledges himself.

On the surface, Jared appears to be a “normal” kid. He even has a girlfriend, whom his father and mother, Nancy (Nicole Kidman), fully expect to become his future wife. They’re disappointed when Jared breaks up with her before going off to college.

But their real shock comes when they receive an anonymous phone call from someone on campus who accuses their son of homosexual leanings. Jared initially denies the charge but eventually admits it may be true. Faced with an ultimatum from his father—change or be ostracized from the family—he agrees to give conversion therapy a try.

Jared’s first days in the program seem harmless enough. Instructors led by Victor Sykes (director Edgerton in a restrained but creepy performance) try to reason the participants out of their sexual preference. You’re not born gay, they’re told, any more than athletic participant Cameron (Britton Sear) was born wanting to play football. And if you choose to be gay, the argument goes, you can choose to stop being gay.  

It’s not long, though, before Jared begins noticing signs that the therapy is neither as effective nor as benign as he’d hoped. A fellow participant urges him to simply play along with the program in order to convince the instructors he’s on his way to a cure. But playing along becomes more difficult when increasingly coercive measures are used to achieve the desired results.

The film reveals Jared’s state of mind with the help of well-placed flashbacks to times when he was torn between his religious beliefs and his sexual longings. He dearly wants to change in order to remain part of his family, but his faith in the therapy falters as his experiences at the clinic become more and more nightmarish. The resulting tension builds to a wrenching climax.

This earnest tale is told with the help of a cast that is almost uniformly fine. I seldom find Kidman’s portrayals completely convincing, but she’s at least adequate as Jared’s concerned mother. Meanwhile, Hedges wins our sympathy as Jared, and Crowe does a fine job of convincing us the Rev. Eamons is a caring parent despite the hell he puts his son through.

Because the story is based on actual people, it ends by relating what eventually happens to the characters’ real-life counterparts. Some of the developments are uplifting, and at least one is surprising. Or maybe it won’t be to those who are good at reading between the lines.

Rating: 4 stars (out of 5)

Boy Erased (rated R) opened Nov. 15 at the Gateway Film Center and AMC Lennox Town Center 24.