Diane Lane — star of this week’s “Let Him Go” — is a reader, so she knows how nervous-making it can be when the movies reimagine a book you love.

Reading “is a personal, intimate experience, just between your ears. No words are spoken. You have an experience in your imagination,” said Lane, whose current read is related to the comic book adaptation she’s shooting in Toronto for the FX network, “Y: The Last Man.”

She speaks of the infinite possibilities of a book, which become limited by choices filmmakers make.

“It’s your own personal poem, so how dare somebody try to interpret the things I pictured when I read it? I have that happen to me when I read screenplays, even. It’s very rare the film will turn out the way I envisioned it,” said Lane.

Still, she committed to “Let Him Go,” based on the Larry Watson novel published by Minneapolis’ Milkweed Editions, because she loved the screenplay, which she read before the book, and because she is a fan of writer/director Thomas Bezucha’s “The Family Stone.”

Said Lane, “Tom has a love for the material and he understood it and I knew he wouldn’t get sidetracked.”

In the 1960s-set movie, Lane plays Margaret Blackledge, who lives on a Montana farm with husband George (Kevin Costner), their son, daughter-in-law and grandson. As the film opens, the son dies in an accident and, soon, the daughter-in-law finds a new husband. After Margaret sees him abusing her grandson, she tells George they need to take the boy back from his mother, a plan that is complicated when the child, his mother and stepfather mysteriously vanish.

Both a family drama and a thriller, “Let Him Go” follows Margaret and George as they try to find their grandson, whom they learn has fallen into the clutches of a notorious family presided over by menacing Blanche Weboy (Lesley Manville, an Oscar nominee for “The Phantom Thread”).

“The story deals with some really tender issues: people processing grief, trying to control the uncontrollable. I think George is processing his grief — dare I say, stepping into someone else’s character’s shoes — by helping his wife deal with hers. It’s a biblical sense of loss to lose your only child and now here’s this grandchild in danger,” said Lane, who was nominated for a best actress Oscar for 2002’s “Unfaithful” and is being touted for another for “Let Him Go.”

Lane is a mom, too (daughter Eleanor Lambert is a model), which helped draw her into the script. Lane felt she knew who Margaret was the minute she got to an early scene when Margaret begins packing, without a word to her husband, so she can go after the boy.

“It’s a sticky wicket to come between a child and mother. That’s what Blanche, Lesley’s character — she’s so good; I love her so much and just to work with her was a thrill — and she says, ‘To come between a mama bear and her child, you could get mauled. Fair warning,’ ” Lane recalled.

Like the packing scene, a lot of the relationship between the Blackledges goes unspoken in “Let Him Go.” Lane compares it to the TV series “Lonesome Dove,” which earned her an Emmy nomination, in how it relies on gestures and glances to convey meaning, rather than words. One thing that helped Lane and Costner is that they’ve played husband and wife before, in “Man of Steel” and “Justice League,” where their kid was a guy known as Superman.

“We wanted more material, Kevin and I. When we parted ways on that set years ago, that was our parting words: ‘We’re going to do this again. We’re going to find something.’ And it’s funny he was the one who said that because I was the one who brought this to him,” Lane said.

She’s glad she did (Costner became a co-producer of the film, too). She thinks the actors’ rapport reads on screen: “We both know what it is if you see somebody look askance at the dinner table. You know what they are thinking. You start responding to that before they’ve said a word. There is quite a bit of symbiotic, almost mind-reading that happens in a long-term relationship.”

Although the title of the movie contains a masculine pronoun, Lane is pleased it’s really about what three women with competing motives will do to protect their progeny.

“At one point, I said something like, ‘Maybe this film should come out on Mother’s Day. There are three mothers and everyone has a mother, so people will be able to relate.’ There are so many perspectives in the movie. I like it when it’s messy that way. I like multiple perspectives and trying to find the one that’s going to win. That’s drama for me and it reminds me of real life,” Lane said.

With “Let Him Go” finally in theaters after pandemic-related delays, the actor is thrilled to be back at work, on “Y: The Last Man.” Since the series is filming in Canada, she had to be declared an essential worker and then quarantine alone in her hotel room for 14 days. She describes the experience as “confronting” because it gave her so much time to think, to feel grateful for work and to read and watch movies.

“I’m thinking of ‘The Unbearable Lightness of Being,’ which is so brilliant. That book was so beautiful in your mind that you just didn’t want anybody to mess it up. And they didn’t,” Lane said.

The good news for fans of Watson’s novel is that — thanks in no small part to Lane — they didn’t mess up this one, either.