Ali Smith revels in etymology. She loves wordplay and puns and homonyms and what Samuel Johnson – another great lexical player – disapprovingly called a “quibble”. I’m sure she knows that “current” means “running” (from the Latin currere). So the proclaimed purpose of her four previous books was always going to be problematic. Four novels, named for the seasons of the year, were written fast and published even faster in an attempt to close the gap between experience and a writer’s response to it. But the trouble with writing about current events is that they keep running on ahead of you. And running away from you. And running in directions you might not have foreseen. (Remember when Covid seemed like the world’s worst worry?) Besides, almost as soon as the series began, it became evident that Smith’s genius is too wayward to be contained within a programme, even a self-imposed one. Smith’s writing is discursive and protean. She writes stories that turn into spells and exchanges that morph from Platonic dialogues into music-hall patter. In the seasonal novels she writes about Rilke and Katherine Mansfield, about Pericles and joinery and the potency of cheap music. She approaches the topic of immigration by way of an excursion to a second world war internment camp on the Isle of Man, and a plot strand relating to a modern boy’s obsession with Albert Einstein, who once lived as a refugee in a hut on a heath in East Anglia. She cracks jokes, lots of them, some of rococo subtlety, some with the raucous rudeness of playground taunts. Her idiosyncratic, staccato fictions touch on modern preoccupations such as the climate crisis and migration and the pandemic, but they do so obliquely, through rainbow-creating prisms provided by history or by the author’s unusually acute sensitivity to craftsmanship and the beauty of material things – be that the curve of a curlew’s beak or the intricacy of the carving on a tombstone. So here comes the scheme-busting fifth part to the quartet. Told (mostly) in the first person by a single narrator, Companion Piece is structurally tighter and more contained than its predecessors. In Spring one of Smith’s lead characters was a film-maker who wanted to shape his film as a series of postcards. Snapshots, glimpses and fragments of time were to be juxtaposed, setting up a jangle of echoes and dissonances and suggestive harmonies. Smith’s whole book sequence has been, similarly, a collage of bits and pieces, of loose ends plaited together. In Summer the word “meander” comes up. Smith, characteristically, goes off on one (a linguistic meander, that is). The character speaking points out that “me-ander” could be an Anglo-German bastard word meaning me/other. In a piece of fiction that is full of parables of foreignness, the wordplay is ideologically resonant. It chimes with the moment when another character sees his file stamped “enemy alien”, as though the two words were synonymous. It is also a gift to anyone trying to grasp Smith’s narrative method. A meander is an apparently purposeless loop whereby a river turns around on itself. Beautiful, baffling but also efficient, it allows water to search out its best way, indirectly but ineluctably, towards the sea. Companion Piece flows straighter. There are only two narrative strands, and they do intersect, albeit supernaturally. The narrator of the dominant one is Sandy, AKA Sand, or Shifting Sand or Sands of Time (in Smithworld the quibbling never stops). Sand’s father is ill. She moves into his house and spends time with his dog. One night she receives a phone call from a woman she was at school with, Martina, who wants to tell her a story. The two women have never much liked each other. Their conversations are grouchy, but the stories they exchange are transformative. Soon Martina’s teenage twins have burst into Sand’s life as well, jabbering in acronymic text-speak, presumptuous and annoying and very funny. This is a lockdown story. People, Sand among them, sit outside the hospital gazing up at the windows of the ward where the people they love are probably dying. When Martina’s family invade her home, Sandy is outraged – not only because she treasures her solitude but because, as Covid-denying anti-maskers, they may be carrying disease. As always, though, Smith feels the deep undertow of history beneath the superficial eddies of the current. Sand walks the dog in a park beneath which lies a medieval plague pit. The supplementary storyline brings in another intruder, a time-travelling female blacksmith with a fairytale aura, who made beautiful things centuries ago. Those things include a famous lock, all wreathed around with wrought-iron ivy leaves, that is at the centre of the story Martina told. Sand is quite like Ali Smith. She has a way with words. She is gay. She is creative and cussed and seldom says what you expect her to say. But there’s not a shred in this book of the fashionable solipsism of autofiction: Smith is too receptive to the world’s variety for that. Lyrical visions alternate with end-of-pier farce and then with exasperated commentary from the narrator about the incongruity between the two. Shakespearean echoes sound through the book. Fables enrich it; fables about fathers and daughters, about interchangeable siblings, about magic beasts and sexual indeterminacy. There is a whole chapter on the origins and varying significances of the word “hello”, a banal little greeting that seems to say that aliens don’t have to be enemies. Companion Piece is shapely, but not conclusive. It doesn’t feel like a coda to the Four Seasons tetralogy, rather an addition to a book sequence for all seasons, with no end in sight. Smith could carry on adding to the writerly collage she is creating through many more volumes. I hope she does. Companion Piece by Ali Smith is published by Penguin (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply.