Nearly 25 years after her luminous and now canonical debut novel, "Housekeeping" (1981), Marilynne Robinson took us to Gilead, a small town in Iowa circa 1957, where the dying old Rev. John Ames was composing a book-length letter that he hoped would someday give his son, then 7 years old, whatever wisdom his own life story might hold. Four years later, in the novel "Home" (2008), we were back in Gilead, seeing the same world and time through the story of Jack Boughton, the scapegrace son of Ames' boon companion, another minister, and Jack's sister Glory, who had come home to tend to her own dying father.

In Robinson's new novel, "Lila," we return to Gilead once more, this time to learn the story of another character glimpsed in the earlier books — Lila, John Ames' much younger, somewhat wild and work-hardened wife. For anyone who has read the first two Gilead novels (not at all a prerequisite for reading this one), Lila's presence in the life they chronicle is a mystery well worth considering — so unlike her elderly, erudite, devout, middling well-to-do husband is she in almost every way.

Although the book begins with scenes of Lila's miserable childhood and her rescue from its worst abuses by an itinerant worker, Doll, these are filtered through the thoughts of Lila already married to Ames and expecting a child. The coming baby gives the story its momentum, fraught as the situation is because of both parents' history — Ames has been a widower for decades, having lost his first wife and infant in childbirth — and Lila's history conjures a different sort of suspense, as we little by little learn what happened along with what is happening now. "And here were the two of them together in this warm light, the same dread feeding on the same hope, married."

Lila's is a sad and sordid story, but what shines from it is the love of Doll, who, however hard and poor she might have been — she killed one person, maybe two, with the knife that is Lila's only memento of her — was "the one who made her live." Like the Queen of Egypt finding "a baby floating in a basket, and after that it was her baby. Live." Like the parable from Ezekiel that informs the novel, as Lila transcribes from the Bible, working on her reading and writing and taking a very literal view of scripture: "He bound himself to Jerusalem when He told her, 'Live,' Ames explains. It's like a marriage."

In those verses can be found what most troubles Lila: "But if God really has all that power, why does He let children get treated so bad?" How can Doll, who did such good, be lost to perdition simply because she doesn't know any better? The mystery of "existence." "Could she have these thoughts if she had never learned the word?" What troubles Lila in her naiveté is what troubles John Ames in all his well-worn knowledge. As Lila tells her unborn child, "The world has been here so long, seems like everything means something."

Where to find that meaning is the question at the center of this book, as Lila's experience of grace in the beauty and power of wild life finds its counterpart in the grace of Ames' reverence and learning and orderly existence — and both characters are given the lyrical expression that is Marilynne Robinson's very own sort of grace.

Novelist Ellen Akins teaches in the low-residence MFA program at Fairleigh Dickinson University. She lives in Wisconsin.