When the third instalment in Ali Smith’s seasonal quartet intruded though my south London letter box, the daffs on the balcony were waning and the tulips were warming up on the touchline to take their place. The book seems to do more or less what the last two did: apply a certain rough magic to the events of the present and the recent past in a way that reflects Smith’s considerable strengths – lightly worn erudition, a terrific ear for dialogue, a lolloping, energetic wit, a high moral seriousness – along with a few ingredients you might feel more ambivalent about, such as a laboured, or belaboured, use of allegory, a few too many dead ends, reverse ferrets and actes gratuits, a preponderance of characters telling each other off and a dash or two of undiluted 1980s magic realism.

Common to all three books is the made-up outsourcing conglomerate SA4A, which does Britain’s dirty work for it in Smith’s version of the mid- to late 2010s. Brit, short for Brittany, who actually is referred to several times as Britannia in case we’re having a particularly slow day, is a detainee custody officer at an immigrant removal centre. Beguiled, then later betrayed and, she will surmise, hypnotised by the unapologetic goodness of the ‘legendary’ Florence, a smart, otherworldly twelve-year-old who goes round making people see the error of their ways, Brit accompanies her from London to the north of Scotland. Here they meet a washed-up television director, Richard, who, poleaxed with grief after the death of his collaborator and one-time lover, a woman named Paddy, and contemplating a dreadful-sounding gig on a film about Katherine Mansfield and Rainer Maria Rilke wafting around a sanatorium, has been rather listlessly contemplating taking his own life. There’s a bumpy ride in a coffee van, some standing stones, a showdown of sorts and a taking back control of that poisoned phrase.

The titular season is ever-present, even addressing us directly at one point. In human terms the theme (lilacs out of the dead land and all that) translates into a series of questions about how or in what circumstances one can allow oneself to feel hope. The motto on Florence’s school blazer reads Vivunt spe (‘they live in hope’). Paddy’s enjoyment of ‘all this green’ shortly before her death made me think of the last interview with her fellow screenwriter (and fellow redhead) Dennis Potter, in which he talked about ‘the whitest, frothiest, blossomest blossom there ever could be’.

That this has some bearing on the current state of the planet, or rather vice versa, is fairly clear (Florence is far from unreminiscent of Greta Thunberg, the Swedish schoolgirl who has been striking against climate change). Changing gear from ‘environment’ to ‘hostile environment’ without glibness wouldn’t be easy, and Smith, who doesn’t really do getting from A to B (I’ve read the climactic scene in the Highlands several times and I’m still unsure how at least one key character came to be there), hardly tries. But she does evoke the sense of a curse lying on the land. The UK government’s policy of taking people who’ve lived here all their lives and locking them up or kicking them out because their papers aren’t in order, of sending people home to a land in flames because they had the temerity to ask this safe and affluent country to help them, shames us all. It’s unleashed serpents of hatred and violence, too, which Smith does not overlook, knitting Twitter rants and the pronouncements of feral politicos into a couple of dense streams of vileness. Brexit itself is little discussed, however – maybe Smith feels she’s covered it in previous volumes; or maybe she’s saving it up for Summer.

Even if the present day constitutes part of the substance of the novel, it’s not ‘about’ the right-here-right-now. Smith doesn’t apply some literary algorithm to raw data, as you could say Gordon Burn did in Born Yesterday: The News as a Novel eleven years ago. Nor is she interested in slotting fictional characters into a real-life scenario, as Nicola Barker did in Clear four years before that. Having read some of her earlier work with intense, though never quite unalloyed, pleasure, I would say that if you’ve enjoyed her before then you’ll love Spring. With the admirable quality we might as well call greatness of soul comes a certain unevenness: for every sharp coinage or snickersnee of dialogue you get people laughing like drains or accusing other people of making it all about them. You might feel that the Legendary Schoolgirl belongs in the same retirement home for worn-out fictional types as the Manic Pixie Dream Girl and the Magical Negro, or that there’s a slight trolley-dash feel to the wide range of approaches, devices and font sizes on display. But you can’t say the book lacks life or originality – or courage, given that it dares to ask, at this slippery moment, what goodness might look like.

I’d almost like to conclude that we get an answer to that question: that the motto of Spring echoes, let’s say, Abe Lincoln’s rousing speech in Bill and Ted’s Excellent Adventure: ‘Be excellent to each other.’ But some characters make a better fist of that than others, in truth. Smith is not so daft as to propose a simplistic thesis of goodness in chains, waiting only for a legendary schoolgirl to turn the key; or to fall for her namesake Winston’s belief that hope lies among the powerless. Indeed, surely we’ve been brought to this pass because certain people allowed themselves to be persuaded by a busload of disaster capitalists and zombie imperialists that they were virtuous because their claws were blunt.