The kids laughed. But when Lowry looked out at the parents, she later wrote, “their faces were like concrete.” She realized that day that she could talk to kids or she could talk to adults, but not to both: “And so I chose the kids.”

It’s a lesson that seems antithetical to this era of dual-tracked children’s stories — a time when 55 percent of all young-adult novels are bought by full-grown adults, when children’s movies are expected to entertain the parents even as the tots load up on popcorn. And so we end up with entertainment like the “Hunger Games” series, or the latter “Harry Potter” movies — thrilling adult stories with kids unnervingly placed in the middle of them. Smaller children get the “Madagascar” movies, in which urbane penguins drop pop-culture jokes into formulaic plot.

Think of the Giver Quartet instead as a fable exploring elemental forces with great care. It’s a story to which many parents may be slow to warm but one that kids will remember their entire lives.

Lowry began “Son” with a mind toward writing about teenage Gabriel, who is curious about his origins and itching to leave the peaceful refuge where he and Jonas ended up. But soon she was looking backward to the mother Gabriel left behind — Claire, never mentioned in “The Giver,” set as it was in a community where pregnancy is left to “birthmothers” whose children are given away unseen to stable, state-selected families. So Lowry set aside the Gabriel chapters (they later became the last third of the book) and concentrated on Claire’s story, the story of a young woman who has lost a son. “I wasn’t aware of it at the time,” she said in her sitting room, pointing to her own heart, “but when I was writing of her yearning to find her boy, that was coming out of my own yearning to have my own son back.”

Claire’s quest to find Gabriel again — and her struggle to decide what to say to him when she does — forces her to decide what she is willing to sacrifice in order to rejoin her child. Scenes of an older, transformed Claire quietly watching her son from a distance are touching even before you consider them in the context of Lowry, now 75, and Grey, buried 17 years ago a wide ocean away from Cambridge. I asked her about the novel’s moving final scene, and she smiled. Behind her glasses her eyes were bright and blue. “Maybe that was wishful thinking on my part,” she said.

Though any parent ought to love the message of “Son” — with its mother and child seeking each other desperately through distance and time — many parents haven’t loved the message of “The Giver.” For nearly 20 years it has been near the top of the American Library Association’s list of banned and challenged books, with objections raised particularly to a frightening scene in which a troublesome baby is euthanized. But Lowry thinks that’s window dressing for adults’ real problem with the book. “What I think they’re really objecting to is the fact that a young person is rejecting the authority and wisdom of the governing body,” she said. “That’s unnerving to them.”

“The Hunger Games,” meanwhile, is squarely in the family tree of “The Giver” but a thousand times more violent and disturbing — and a thousand times less artful. “I’m not terribly conversant with children’s literature in general,” Lowry said. “I tend to read books for adults, being an adult.” But she read the first book in Suzanne Collins’s megasuccessful trilogy as a judge for a literary prize. “I could certainly see why kids love it. It’s suspenseful. The plot moves right along. But I was troubled by the fact that it’s children killing children.” She says this so matter-of-factly that I’m reminded anew of the absurdity of the fact that parents should be outraged at such a story, yet millions of them have spent hundreds of millions of dollars on books and movies in which children murder other children for sport. (I’ve spent about $75 myself.)