Three-quarters through her series of novels based on the four seasons, Ali Smith has made it clear she's got a lot on her mind. "Spring" pivots off themes from "Autumn" and "Winter" — the toxic brew of old hatreds and new media, how art staves off racism and anti-immigrant fervor — while pushing formal boundaries under the deceptive guise of a loose, conversational voice. She's the most audacious political novelist in the language, and with Brexit and the Trump presidency she's met her moment.

Most of the action in "Spring" unfolds over a few days in October 2018, bifurcated into two narratives that gradually weave together. On a railway platform in Scotland, Richard Lease, a middle-aged television and film director from London, contemplates suicide. He's mourning the demise of his colleague and cherished friend, Patricia "Paddy" Heal, who had been intrigued by a quirk of literary history: In 1922, poet Rainer Maria Rilke and novelist Katherine Mansfield were lodgers at the same Swiss hotel. Had they known each other?

In Smith's second story, Brit Hall, a young woman who works in a kind of prison for detained refugees, encounters Florence, an ethereal black girl who literally hypnotizes all who cross her path. Florence persuades Brit to go off with her to a village in Scotland, the same where Richard Lease awaits his appointment with death. From these strands Smith spins a beguiling, faceted tale, stirring with underground resistance, ordinary folks doing extraordinary things in the name of morality.

Make no mistake: Smith's vision is dark, dark, dark. Our refugee crisis, sex trafficking, the West's pathetic responses: All weigh heavily on her. But as in Mohsin Hamid's "Exit West" there's a whiff of magic, the flicker of redemption. "Spring" skips playfully across time and perspectives. In flashbacks, Paddy limps through the last lap of cancer, vibrant and curious to the end. Brit's an EveryBrit, bored by her job, put off by the detainees in her care, but opening like a flower under the sunny gaze of the mysterious Florence. Richard finds his will to live again. The Earth stubbornly turns; spring looms closer.

"The air lifts. It's the scent of commencement, initiation, threshold," Smith writes. "Primroses deep in the ivy throw wide the arms of their leaves. Colour slashes across the everyday. The deep blue of grape hyacinths, the bright yellows in wastelands … now the branches stiffen, the ends of the twigs glow like low-burning candles."

The prose here is vintage Smith: slangy and acerbic but speckled like a quail's egg with lyrical insights. What Richard observes about Mansfield's writing could also apply to this author: "She is funny … brilliant, tricksy, arch, flirty, charming, and full of an unfathomable energy for someone … full of black moods." With its inventive twists, all-too-human cast and wrenching political reckoning, "Spring" ushers in a fresh season of Ali Smith's genius. Summer beckons, just ahead.

Spring by Ali Smith

Hamilton Cain is the author of "This Boy's Faith: Notes From a Southern Baptist Upbringing" and a member of the National Book Critics Circle. He lives in Brooklyn.

Spring
By: Ali Smith.
Publisher: Pantheon, 335 pages, $25.95.