Nick Hornby’s novels revolve around a different theme or conceit, be it music (“High Fidelity”), attempted suicide (“A Long Way Down”) or the innocent joys of 1960s TV (“Funny Girl”). But what links the books, what powers them, and what truly lies at the heart of them are brilliant depictions and examinations of relationships — platonic, romantic and everything in between.

Hornby’s latest novel, “Just Like You,” sees him dispensing with other topics and focusing entirely on the relationship between his two lead characters and its impact on those around them. He doesn’t sell his reader short, for this love affair is like nothing we have encountered before in his fiction. Marked by significant differences and fraught with huge uncertainties, it requires both parties to compromise to make it work and resemble more than just “something between things.”

We are in London in 2016. Lucy is a middle-aged, middle-class white mother. Soon to be divorced, she is now ready to start dating again. Joseph is a 22-year old Black man who lives at home with his mother and dreams of becoming a DJ. For the moment he juggles many part-time jobs, including working behind the counter of Lucy’s local butcher’s shop. He is mesmerized by this pretty brunette whose smile “warmed even a refrigerated room”; she is attracted to this young man who, according to one of her friends, resembles a young Denzel Washington.

Joseph acquires another job: babysitting Lucy’s children while she goes out and weighs up author Michael Marwood as a possible long-term partner. But she quickly realizes Joseph is her ideal man, despite his being half her age and from a different social and cultural background. Love blooms, and for a while they manage to overlook their dissimilarities, ignore the gulf of an age gap, and win approval from each other’s friends and families. “We keep jumping over hurdles,” says Joseph. But will one obstacle eventually prove insurmountable? And if they do clear them all, what shared future awaits them?

Once again, Hornby writes about human connection and interaction with facility and acuity, and always in the most engaging prose. He makes us care deeply for his two protagonists as they follow their instincts — falling in love, falling apart, then making another go of it. Each is aware of what keeps them strong, but also what threatens to destabilize them.

Joseph is embarrassed by Lucy’s dancing, uncomfortable at her dinner parties, and unable to understand her concerns about Brexit and other state-of-the-nation issues; Lucy views her young lover as “a wonky table, a glass skylight, thin ice” — any increased pressure on her part and she could damage what they have and drive him into the arms of someone nearer his age.

As ever, Hornby’s characters articulate their hopes and fears throughout expertly crafted dialogue and well executed scenarios. Astute and emotionally involving, this is a bittersweet tale about opposites attracting, then trying to stay together.

 Malcolm Forbes has written for the Times Literary Supplement, the Economist and the New Republic. He lives in Edinburgh, Scotland.

Just Like You
By: Nick Hornby.
Publisher: Riverhead, 355 pages, $27.