When the documentary “Markie in Milwaukee” begins, Markie Wenzel, a middle-aged transgender woman, is in the process of eradicating the records of her own existence. When we meet her, nearly a decade ago, she’s beginning the process of “detransitioning,” which in her case meant legally changing her name, discarding her hormone treatments and wearing men’s clothes in public.

Markie came out in 2006 at the age of 46, and her wife, her children and her church painfully rejected her. Shortly thereafter, she met the director Matt Kliegman, who was flying through the Milwaukee airport where Markie works. Kliegman struck up a friendship with her when she was newly open about her gender, and he began to film her. His movie is the result of about 10 years spent documenting Markie’s life, her faith as an Evangelical Christian and her strained relationship with her family.

Whether transitioning or detransitioning, Markie invites the filmmakers into her life with tremulous vulnerability. The documentary plainly lays out the impasses she is facing. As a woman, Markie is more fully realized but utterly alone. If she lives as a man, she is self-denying, but her community no longer holds her at a distance.

Markie is generous with the camera, and her candor lends the film power. She grants access to her personal archives, sharing tapes from her former life as a pastor and photos of her once-secret makeup tests. The film doesn’t waste her openness or her willingness to use the documentary as a kind of therapeutic space.

But if Markie is undeniably compelling as a subject, the film doesn’t quite match her bravery and her willingness to explore uncharted territory. There are plenty of fly-on-the-wall observations, but little play or introspection besides what Markie is able to offer.

Markie in Milwaukee
Not rated. Running time: 1 hour 32 minutes. Rent or buy on Apple TV, Google Play and other streaming platforms and pay TV operators.