With her flawed but poignant new book, “Lila,” Marilynne Robinson has returned to the central characters in her Pulitzer Prize-winning novel, “Gilead” (2004) — the aging minister John Ames and his much younger wife, Lila — and to the themes of alienation and separateness (and the possibility of belonging) that animated her astonishing debut novel, “Housekeeping,” more than 30 years ago.

“Gilead,” set in a small Iowa town, took the form of a letter that the dying Ames wrote to his son who was turning 7 — a meditation on their family history, his religious faith and his regrets and hopes. “Lila” — which might well have been titled “Balm in Gilead” — is his wife’s story, chronicling her precarious childhood and youth, and her efforts to come to terms with that legacy of emotional damage. The novel ends with the birth of her son, whom Ames would address, years later, in “Gilead.”

Writing in lovely, angular prose that has the high loneliness of an old bluegrass tune, Ms. Robinson has created a balladlike story about two lost people who, after years of stoic solitariness, unexpectedly find love — not the sudden, transformative passion of romantic movies and novels but a hard-won trust and tenderness that grow slowly over time.

Image Marilynne Robinson Credit... Kelly Ruth Winter

The novel is powerful and deeply affecting, but also hobbled, at times, by the author’s curious decision to tell the story in the third person, robbing it of the emotional immediacy of “Gilead” and resulting in occasional passages that seem to condescend to Lila, as an uneducated, almost feral creature. Perhaps Ms. Robinson decided to tell the story in the third person out of concern that such an unlettered girl might not have the language for communicating her state of mind, or perhaps it was difficult to find a voice for Lila that could comfortably address the big existential questions of life while remaining authentic and plain-spoken.