Some years ago, Dani Shapiro's husband and son were driving home from a townball game when teenagers threw a bottle of salad dressing from the top of an embankment. It shattered in the street, missing their car by a fraction of an inch.

"When my husband got home he told me if it had been a second earlier, that salad dressing would have hit the windshield and they would have had a terrible accident," Shapiro said in an interview from her home in Connecticut. "And I thought, salad dressing! I never considered a bottle of salad dressing becoming a means of devastation."

The lesson from this — the lesson that Shapiro already knew, thinks deeply about and has woven into her new novel, "Signal Fires" — is that randomness, chance, quick decisions to turn left or right, to pause or accelerate, can change a life in an instant.

"It's something that comes up again and again in the novel," said Shapiro, who will be in St. Paul for Talking Volumes on Oct. 28.

"Everything we do matters. And if we thought about that all the time we wouldn't be able to get out of bed. But if we actually internalize that to some degree I think it can define what it is to be a human being."

Shapiro, 60, is as well known for her bestselling memoirs as she is for her novels. She is also the host of the podcast "Family Secrets," which explores long-buried secrets and the liberation that comes from setting them free.

"One of the things I've learned is that when there is a secret that is being kept, there is shame," she said.

Secrets suffuse "Signal Fires," which opens in 1985 when a teenage girl tosses her car keys to her younger brother. She has been drinking, but he doesn't know how to drive, and the result is a crash and a terrible death. The rest of the novel deals in various ways with the repercussions from that choice — including the psychic pain of silence.

A second narrative thread involves a brilliant 10-year-old boy named Waldo who is fascinated by the firmament and who finds the enormity of outer space to be grounding and soothing — despite the fact that this passion baffles and enrages his father.

The way that Shapiro braids these two strands together, shifting points of view, time and location, makes for a satisfying, haunting read.

And yet, the book might never have been written had Shapiro not gotten the sudden urge to clean her office. (Another fine example of the life-changing repercussions of ordinary decisions.)

'A manuscript. Just sitting there.'

It was early in the pandemic, and her work had ground to a halt. "Everything about the world was trembling in so many ways," Shapiro said. "The pandemic and the BLM uprising and the world was on fire and how is it possible to write anything of any relevance?

"Just about every artist and writer and human I knew was in this state of paralysis." And so she turned her attention to clutter.

"And in my office closet, sitting there on a shelf after I had taken out a lot of what was obscuring it, was a manuscript," she said. "A 120-page manuscript. Just sitting there neatly."

Shapiro had begun the manuscript 10 years before, determined to structure it moving backward chronologically in time, but after 120 pages she'd gotten stuck.

"There's a reason why there aren't many books that do this," she said. "The reason is you run out of runway. I wrote the first part that takes place one night 2010 and then I wrote a part that took place one night in 1999. And then If I wanted to continue backward, then Waldo would not be born yet, and that was a problem! I essentially wrote myself into a corner."

At the time, she discussed the conundrum with Jennifer Egan, her friend and fellow novelist. "And Jenny said, 'Chronology is boring whether you're going forward or back.' She said, 'If you're upending time, why be chronological about it?' And I knew she was right but I didn't know how to do it. I was heartbroken. I put the pages in a drawer and really thought this is the one that got away. I didn't think I would go back to it."

But in 2020, sitting in her office re-reading those pages, the way forward became clear.

"I remembered everything I liked about these people," she said. "And the next thought was who would they be now that it's 2020? And my head sort of exploded. Who would Waldo be, he was 11, who would he be? Oh, he'd be a college student. And who would Ben be? And Theo, who was a young chef, with this restaurant, what would he be doing in the middle of the pandemic?

"It all just aligned itself in my brain in this very thrilling, exciting way. And I suddenly saw how I could break it up. And how I could turn it into a more prismatic narrative."

The book is written in sections that move back and forth in time and point of view — from the car accident in 1985 to a single night in 2010 to New Year's Eve at Y2K to the early days of the pandemic in 2020.

"They needed to grow in that drawer for those 10 years," Shapiro said. "And I needed to have a series of life experiences during those 10 years that allowed me to become the writer that described them."

Between writing those 120 pages in 2010 and picking them up 10 years later, Shapiro had experienced a remarkable revelation, which became the focus of her fourth memoir, "Inheritance." In 2016, after submitting her DNA to a genealogy website, she learned that her father was not her biological father.

She tracked down her biological father — a man who had sold sperm in order to get through medical school. And in 2020, when she re-read that missing manuscript, she realized that the character of Ben was a dead ringer for her biological father.

"I wrote and conceived of the character of Benjamin Wilf years before I knew that I had a biological father that was other than my dad who raised me and who I adored," she said. "And when I gave the manuscript of 'Signal Fires' to my son, he said, 'My God, it's him.'

"What do you do with that? And it's not just a physical resemblance, it's also his being a physician, his having a certain kind of even temperament, very even-keeled, very gentle and kind but misses nothing. If I had created that character after meeting my biological father I might have assumed that I must have absorbed him in some way. But that's not what happened."

The strangeness of this reinforced her belief that everything is connected — the living and the dead, the past and the present, all people, all living things. It's a theme that echoes through the book primarily through the observations of earnest young Waldo.

The scenes where Waldo stares at the constellation program on his iPad and explains his understanding of the universe are among the most powerful in the book. His app — called Star Walk, a real app — can call up the night sky from any place in the world, from any year in history.

Late in the book, as he scatters his mother's ashes, he compares death to the burning out of a star. "I'm oversimplifying," he tells his father. "But you get it. The stardust eventually makes other stars."

Everything is connected, Shapiro said. "The night sky here is connected to the night sky there and everything that is going to happen has already happened.

"What do we mean to each other, what are our connections to one another as human beings? Why do we sometimes feel a connection to people we've just met? That connection can be positive or negative, it can just be a feeling of 'I know you.' Somehow, we've traveled this road together before."

Laurie Hertzel is the senior editor for books at the Star Tribune. @StribBooks

Signal Fires

By: Dani Shapiro.

Publisher: Alfred A. Knopf, 240 pages, $28.

Event: Talking Volumes, 7 p.m. Oct. 28, tickets $28-$30, https://bit.ly/3AU2zes

Excerpt:

"You're seventy-four," Waldo says. "You did the math in your head."

"Look." Waldo hands Ben the device, which is heavier than it looks. "There it is."

It takes Ben a few seconds to realize what he's looking at: the sky of his birth. "Canis Major," Waldo says. "A very cool constellation. Canis Major contains Sirius — the Dog Star. The brightest star in the night sky."

Ben touches the screen, tracing the dog with his index finger: a large-pawed animal, seated, his head alert, as if awaiting further instructions. Waldo leans over and taps a circle in the upper-left corner of the screen.

"Canis Major is a constellation, included in the second-century astronomer P ... Ptol ... Ptolemy's forty-eight constellations," Waldo reads out loud, "and still included among the eighty-eight modern constellations. Its name is Latin for 'greater dog,' and it is commonly rep ... rep ... "

"Represented," Ben prods the boy. "I know!"

"Sorry."

" ... represented as one of the dogs following Orion, the hunter. See also Canis Minor, the 'lesser dog.' "

"I'd certainly rather be born under a greater dog than a lesser dog," Ben says.

Waldo glares at him. "You're making fun of me."

"No."

"You're joking, then."

"Well, yes."

"This isn't a joke."

In the glow cast by the contraption, Ben sees that Waldo's eyes are brimming with tears.

"Okay, buddy." Ben pats his hand awkwardly. "I'm sorry. I didn't mean — "

"Everybody thinks this is stupid, or something."

The boy is trying hard not to cry, but his sharp little chin is quivering.

"Who's 'everybody'?" Ben asks.

"I dunno."

"C'mon."

A long pause, during which Ben notices that the skin around the boy's nails is raw and puckered, picked and bitten to the quick.

"My dad," Waldo finally says.

Excerpted from "Signal Fires" by Dani Shapiro. Copyright © 2022 by Dani Shapiro. Excerpted by permission of Alfred A. Knopf, a division of Penguin Random House LLC. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.