The new Diane Lane-Kevin Costner movie Let Him Go is the kind of old-fashioned entertainment that Hollywood rarely makes anymore, which is a shame, because this well-crafted thriller aimed at adults is the best studio movie I've seen in months.

After playing Clark Kent's parents in Man of Steel, Lane and Costner reunite here as another wholesome duo, Margaret and George Blackledge, who live quiet lives on a Montana ranch — until that peaceful existence is shattered by the tragic death of their adult son James, who leaves behind a wife, Lorna (Kayli Carter), as well as a young son of his own.

Three years later, Lorna remarries a man named Donnie Weboy (Will Brittain), whose family does not attend the loveless ceremony. We never see what attracted her to Donnie in the first place, and it's implied that because she's a vulnerable widow with a child, she's just grateful to have a man. Of course, it's not long before the abusive Donnie reveals his true nature and slaps both his new bride and stepson as Margaret looks on in dismay. She feels a responsibility to her grandson, Jimmy, and when she goes to check on him the next day, she's shocked to learn that her closest kin packed up and left in the middle of the night.

Margaret quickly resolves to free Jimmy from the evil clutches of Donnie and his crooked clan, and being a retired lawman himself, George refuses to let her go alone. The two of them seem to understand the stakes of the vigilante mission they've signed up for. After all, Margaret acknowledges she has no legal standing to take Jimmy home with her, but she trusts her instincts, and so does George. Though the Blackledges try to take Lorna's feelings into account as well, they're aware they can't put much stock in them, given how scared Lorna is of Donnie and what he might do if she tried to leave him.

When Margaret finally does track down a Weboy in the flesh, she insists she just wants to say a proper goodbye to her grandson, but you know her real plan is to say goodbye to Donnie. Either way, it's off to the other grandmother's house we go, and the film begins to take on a more sinister tone in its second half.

The Weboy family lives off the grid in North Dakota, and they sure look like a nasty bunch, even though we're never quite clear what makes them the Corleones of the countryside. All we know is that the Godfather in this case is actually the Grandmother, Blanche Weboy, played to menacing perfection by scene-stealing English actress Lesley Manville (Phantom Thread), who goes "big" here.

Blanche is the intimidating matriarch of this dangerous family, and she rules over her boys with an iron fist. When eldest son Bill (Jeffrey Donovan) invites George and Margaret to dinner, neither side is shy about putting their cards on the table. The gripping scene crackles with tension, but the outcome is inevitable. Blanche is simply holding better cards, and she knows it. Her poker face leaves much to be desired, though the character's loud-and-proud chutzpah is part of her frightening appeal.

When Martha tries to appeal to Lorna's maternal instincts, it backfires in a bad way, and even though the resulting confrontation lands George in the hospital, a complaint to local law enforcement doesn't end much better. "He's a Weboy now," the sheriff tells the Blackledges of their grandson. But Margaret would rather die than see Jimmy grow up in that household, and George would rather die than see his wife in such pain, so, knowing how determined she is to get the boy back, he sets out on a solo mission to rescue Jimmy -- by any means necessary.

Let Him Go is a mature meditation on grief disguised as a revenge-driven home invasion movie, though it's not always clear whose home has been invaded here. The title contains multiple meanings -- are the Blackledges telling the Weboys to let Jimmy go, or is it George and Margaret who have to let Jimmy go? Perhaps the titular "him" refers to their fallen son... or someone else entirely. What sets Let Him Go apart from its B-movie cousins is that writer-director Thomas Bezucha doesn't embrace the story's genre elements, but rather, its more sensitive inclinations. Though the body count soars in the film's shoot-'em'-up climax, this film doesn't revel in death or its details. Instead, death is something to get out of the way, as Bezucha seems compelled to accentuate more compassionate moments, such as the Blackledges' fairly contrived but still welcome relationship with a young Native American man played by Booboo Stewart. Best known for playing Seth Clearwater in The Twilight Saga, Stewart shows nice depth here as a peaceful drifter who helps George and Margaret pull off a hard-fought family reunion.

The script (based on the book by Larry Watson) separates George and Margaret more than I expected, but Lane and Costner have good chemistry together, though it's the latter who ultimately comes off as better-suited for this kind of pulpy material. Costner can communicate so much with just a simple look, and he brings a stoicism to George that serves the character well. I also appreciated everything that went unsaid by the couple, who have the kind of easy rapport that comes with being together for decades. They don't need to talk all the time, because they're comfortable enjoying the silence together. In fact, those brief scenes speak volumes regarding the strength of their relationship.

There are issues, of course. Not only is Lorna's perspective sorely lacking, but at 113 minutes, Let Him Go is about 10 minutes too long for this kind of film, and as such, its impact is somewhat dulled by a leisurely pace that I suppose reflects its midwestern setting. But stories like this also need time to breathe. Its heroes aren't 30-year-old superheroes, but a couple of grandparents who operate a ranch in Montana. This is a sensitive vigilante tale, and despite a fiery third act, you have to realize that it's a slower burn than the action movie promised by its trailer.

I watched Let Him Go twice in one setting with two completely different audiences -- a couple in their 30s and a couple in their 60s, and there's no question that it appeals to an older crowd. Once you know that going in, I think you'll better appreciate the surprising emotion this film has to offer beneath its slick, suspenseful surface.

Grade: B+

Let Him Go will be released in theaters on November 6th.