In December 2003 the Broken Man tried and failed to take Quintana — who lay unconscious from pneumonia and septic shock in a New York City hospital — and instead claimed her father, who suffered a heart attack shortly after returning home from a visit to see her. Quintana held on for 20 months, but died in August 2005 at 39.

Ms. Didion’s heartbreaking new book, “Blue Nights,” is at once a loving portrait of Quintana and a mother’s conflicted effort to grapple with her grief through words: the medium the author has used throughout her life to try to make sense of the senseless. It is a searing inquiry into loss and a melancholy meditation on mortality and time.

The volume is also a bookend of sorts to Ms. Didion’s extraordinary 2005 bestseller, "The year of magical thinking" which chronicled her struggle to come to terms with the death of her husband of four decades, while navigating the alarming medical labyrinth into which her daughter had been plunged. Those events, she wrote, “cut loose any fixed idea I had ever had about death, about illness, about probability and luck, about good fortune and bad, about marriage and children and memory, about grief, about the ways in which people do and do not deal with the fact that life ends, about the shallowness of sanity, about life itself.”

Whereas “Magical Thinking” was raw and jagged and immediate — the work of someone who prized order and control and found herself suddenly spinning into madness — “Blue Nights” is a more elliptical book: the work of a survivor trying to understand the daughter she has lost, even as she surveys the receding vistas of her own life, as age and illness and bereavement leave her feeling newly vulnerable and alone.

In these pages the reader can feel Ms. Didion circling her subject, searching for a way to write about what turned out to be the worst fulfillment of the worst fears she’d harbored from the instant she became a mother: a fear of “swimming pools, high-tension wires, lye under the sink, aspirin in the medicine cabinet,” a fear of “rattlesnakes, riptides, landslides, strangers who appeared at the door, unexplained fevers, elevators without operators and empty hotel corridors” — in short, a fear of the perils of ordinary life that could threaten her daughter.

Ms. Didion also circles the subjects that continue to unnerve her: her worry that she did not sufficiently understand the fears of abandonment Quintana had, as an adopted child; her worry that she and her husband somehow imposed adult expectations on Quintana when she was a girl; her worry that Quintana saw her mother as frail and needing care. (“One of her abiding fears, I learned much later, was that John would die and there would be no one but her to take care of me.”)

On the eve of Quintana’s 11th birthday, Dunne described her as approaching “adolescence with what I can only describe as panache” — watching “her journey from infancy,” he went on, “has always been like watching Sandy Koufax pitch or Bill Russell play basketball.”

Ms. Didion, who collaborated with Dunne on screenplays, writes about how the young Quintana could see a film like “Nicholas and Alexandra” — “a truly harrowing story” that “placed both parents and children in unthinkable peril” — and casually describe it in Hollywood default terms as a movie that’s “going to be a big hit.”

But along with Quintana’s composure and sophistication, Ms. Didion writes, there would later be bouts of “suicidal despair.” There were depression and anxiety, and drinking to blunt the anxiety and depression, and there were visits to doctors, who had disparate diagnoses of “manic depression,” “obsessive-compulsive disorder” and “borderline personality disorder.”