One of the great gifts the cinema has bestowed on us has been the lovely third act comeback afforded writer-director Paul Schrader.

A figure from the “Taxi Driver,” “Hardcore” and “Raging Bull” era of iconoclastic American cinema, he was all but left for dead in the age of “content” and comic book cinematic juvenalia.

But here he is, Scorsese’s greatest screenwriter and a damned fine writer-director (“Cat People,” “Light Sleeper,” Light Sleeper”) in his own right, serving up stories with patience, depth, metaphor and moral and cultural topicality, our most Christian filmmaker plumbing the depths of our modern mortal souls.

Religion isn’t in the foreground of the latest from the writer/director of “First Reformed.” But it’s a subtext lying just beneath the surface of “Master Gardener,” a story of redemption and cultivating one’s way towards the renewal that every growing season promises.

The Aussie Joel Edgerton (the film “Animal Kingdom,””The Great Gatsby,” “Loving”) gives one of his finest performances as our narrator and protoganist, a true believer in the nobility of the garden and the power of working with plants to restore the soul.

“Gardening is a belief in the future,” Narvel Roth narrates, floridly filling pages of his journal with reveries of flora and pedantic asides on the history of this hobby, which he treats with the reverence of one newly-converted to the faith that saved him.

The way he talks, we might think he’s a college lecturer on the subject. But the way Narvel carries himself, the cut of his hair and the slicked-down way he wears it, suggests something harder. Narvel is a man with a past, and we know it long before he compares a particular floral scented “buzz” as “like that you get just before pulling the trigger.”

Sigourney Weaver plays his old money boss, the owner and steward of Gracewood Gardens on her family’s estate, where “four generations of curated botany, horticulture and display” is nothing to sneeze at.

Norma is patrician without being patronizing, devoted to an annual charity auction that lets her gardens raise money for Meals on Wheels, and informal enough to relish Narvel’s sarcasm about watching “grown men in pastel pants outbid each other for a flower,” even calling Narvel “Sweet Pea” with more affection than we’d think possible, considering the diffence in their classes.

But Norma needs a favor. Her troubled grandniece, daughter of an addicted daughter of her late sister, needs help straightening out her life. Maya is 20ish, “of mixed blood,” and Narvel is to take her on as a an apprentice.

Narvel asks questions of Norma, and when Maya (Quintessa Swindell of “Black Adam”) arrives, he asks more. He sizes her up, senses her past and her present. He embeds her with the garden staff, teaches and mentors her. And when her messiness cannot be hidden, he asks her a question everyone could stand to hear on occasion.

“Are you satisfied with your life?”

If you’ve read or heard anything about “Master Gardener,” you’ve figured out the pun in its title. Narvel’s big secret isn’t a secret to Norma, his U.S. Marshal Service handler (Esai Morales) or the viewer, the first time we see him peel his shirt off in the comfort of his garden cottage.

Narvel’s swastika tattoos connect with his camo-clad militant white supremacist past which we glimpse in flashbacks. This was who he used to be, a cruel “master race” cultist consumed by hate and the violence that spins out of that.

“I found a life in flowers. How unlikely is that?”

But this isn’t just his road to redemption story. “Master Gardener” is about planting seeds, culling dead or dying branches and making room for new growth. Whatever he’s held onto from that past life, he’s cultivating something in Maya that could save her.

Edgerton gives one of his most compact and introverted performances as this man “saved” by “manure” and what can grow in it. Weaver is similarly quiet, almost subdued, the very embodiment of a widowed woman of property. And Swindell slides easily into the rhythms of the world Schrader conjures up, where even the arguments have a gentility about them.

The grandniece is “impertinent,” a deadly sin in a world this ancient and ordered.

Schrader makes more melodramatic choices in the film’s later acts, some of them unfortunate. Every time you see a 50ish leading man linked romantically with a 20something beauty, the viewer is free to consider that the aged writer-director’s wish fulfillment fantasy.

But he still manages to trip up expectations, leaning into “man of violence returns to violence” genre conventions, even casting his hero and heroine into the wilderness, but letting them and his movie find their footing and their core values as they do.

There can be no renewal, after all, without a periodic and brutally unsentimental cutting, killing or trimming.

Rating: R for language, brief sexual content and nudity

Cast: Joel Edgerton, Sigourney Weaver, Quintessa Swindell, Esai Morales

Credits: Scripted and directed by Paul Schrader. A Magnolia release.

Running time: 1:51