The second in a seasonal quartet, "Winter" begins on Christmas Eve, at a moment when Christmas music "gives a voice to spirit at its biggest, and encourages spirit at its smallest, its most wizened, to soak itself in something richer," as Sophia Cleves, our protagonist, reflects.

And indeed Sophia, "a once stellar international businesswoman who'd come down here [to Cornwall] to retire," is sorely in need of encouragement. She and her 30-something son Art begin the book with smallish spirits, each with a narrow perspective on the world, and Christmas offers an opening — through which, as in "A Christmas Carol," ghosts of Christmas past and promises of Christmas future can make their salutary way.

As in many of Ali Smith's books, disrupters arrive to stir the plot.

Art, on the eve of a Christmas visit to his distant, difficult mother, suddenly finds himself without the girlfriend who was supposed to go along. Desperate, he hires a stranger, a young woman discovered at a bus stop, to play his girlfriend. Thus Lux, as the girl calls herself, becomes Charlotte, and we are as good as guaranteed a few complacency-shaking surprises — which Lux duly delivers. Meanwhile, the real Charlotte has taken over Art's Twitter account and is posting startling tweets under his name; for instance, announcing the sighting of a Canada warbler in Cornwall, an outrageous (in bird-watching circles) claim with its own disruptive and amusing consequences for the Christmas visit.

Art, in his off hours, writes a blog called Art in Nature, describing largely imaginary encounters with the natural world. He is, in Charlotte's judgment, "not the real thing … a selfish fraud," immune to the political realities of the world he writes about.

Similarly, Sophia, an indifferent mother, is disconnected from the world around her. Shut up in her enormous house with its 15 empty bedrooms, with little contact and less food, she is visited a few days before Christmas by a disembodied head — a child's, perhaps — that haunts her through the holidays, slowly shedding its features until it becomes a smooth, weighty stone.

“Winter” by Ali Smith

In contrast, Sophia's estranged older sister Iris is thoroughly engaged. Home for a break from working with refugees in Greece, she comes at once when Art calls, alarmed at his mother's state. With Iris and Lux as catalysts, scenes from Christmas past unfold, and our narrow views of Sophia and Art widen and deepen, filled with the secrets and substance of their histories, even as the characters themselves seem to expand.

As in Sophia's case, for Art this enlargement is announced by a hallucination — "not a real thing," as Lux tells Iris, whose response speaks for the book's own expansive spirit: "Where would we be without our ability to see beyond what it is we're supposed to be seeing?"

Ellen Akins is a writer and writing teacher in Wisconsin.

Winter
By: Ali Smith.
Publisher: Pantheon, 322 pages, $25.95.