When Ali Smith set out to write four books in four years, one for each season beginning with autumn, little did she know what summer had in store. The crises that riddle the quartet’s first three volumes — including Brexit, climate change and corrupt politicians — seem almost mundane, compared with the catastrophe rumbling through “Summer.” Worse yet is the apathy that ensues. “Everybody said: so?” the wise narrator tells us, “As in so what? As in shoulder shrug, or what do you expect me to do about it?” But rather than rattle on about the evils of indifference, she says, “here’s something I once saw.”

It is an image from a film made in London shortly after the Second World War: a slight young man, burdened with two suitcases, balanced on a narrow brick ledge at the top of a tall building — and doing a joyous and frantic dance. “How can what he’s doing be so wild and still so graceful, so urgent and blithe both at once?” An apt metaphor for the storyteller’s art, this is also a fair way to think about the bright, beleaguered people we are about to meet, acknowledging gravity with insouciance, evoking grace in the face of calamity.

In fact, Grace is first up, at home in Brighton, in the U.K. Once an actress, she is trying to place a misremembered line: “Whether I shall turn out to be the heroine of my own life”; while Sacha, her charmingly snarky 16-year-old daughter, is also trying to source a line — for an essay on forgiveness, meant to mark one week since Brexit. After a prickly exchange (”The internet is a primary source,” Sacha insists), a quick hug stirs the warmth Sacha remembers asking about as a child “because it felt so nice and her mother’d said that’s your inner summer.”

Add in Robert, Sacha’s brainy, ornery 13-year-old brother, who is fascinated by Einstein, in particular his visit to Norfolk in 1933 — and most of the elements that thread through the novel have been put into play: Dickens, Einstein, forgiveness, forgetfulness, politics, language. Then Robert superglues a glass egg timer to Sacha’s palm (”time on ur hands”), and the plot is set in motion. Sacha is rescued by Art and Charlotte (a couple we met in “Winter”), who are on their way to deliver a memento to Daniel (an ancient man we met in “Autumn”) — in Norfolk! So somehow, Grace, Sacha and Robert end up accompanying Art and Charlotte to Norfolk, and all of their stories unravel and ravel at once.

At the novel’s center is Daniel, drifting dreamily between present and past. A German emigre, he was held as an “enemy alien” at a British internment camp during World War II, while his younger sister Hannah was secretly shepherding Jews out of Nazi Germany. Smith gracefully interweaves the stories of Daniel and Hannah with those of the visitors, letting us see what the characters cannot — the subtle links between traumas old and new.

In a novel that is, like all of Smith’s, rich with references, characters quick to share stories about artists and their work, and the misfits and heroes of history, “Summer” is more than a perennial season. It is the bravura performance of a writer, poised at the edge of the day’s vast darkness, gathering all the warmth and light of our inner summer.

Ellen Akins is the author of four novels and a collection of stories, “World Like a Knife.”

Summer

By Ali Smith

Pantheon. 400 pp. $27.95