Carmen Callil withdrew from the judging panel of the Man Booker International prize when the other judges decided to give its award to Philip Roth. Roth, she said, "goes on and on and on about the same subject in almost every single book. It's as though he's sitting on your face and you can't breathe." Which was a funny thing to say, not just for the obvious reasons, but because the subject of breathlessness comes up quite frequently in his latest novel  first published in this country some seven months before Callil made her intemperate remarks.

The breathlessness in question comes as a result of polio, an epidemic of which strikes Newark, New Jersey, in the baking summer of 1944. This is surpassed only by death as the worst thing that can happen when polio strikes; that, and the fact that its victims are chiefly children. The novel's chief protagonist, 23-year-old Bucky Cantor, an athletic young man declared unfit for military service due to his poor eyesight, agonises about the appalling fates that await the victims: he's a playground director, God-like in the eyes of his young charges, a source of unimpeachable rectitude and kindness. But he can do nothing to prevent the spread of the disease. And as someone supremely active and fit, he can think of no worse existence than that of being trapped inside an iron lung.

Now, as for going on and on about the same thing, you could argue that once again, Roth is going on about death, but that doesn't quite sound right here. What Roth is going on about in this book  and I would like to express this as tentatively as possible, because this is not an easy novel to second-guess, or, if you like, reverse-engineer  is the malicious capriciousness of fate, or the fallibility of God.

This is, and is not, classic Roth. It is, in the sense that here he has returned to the scene of his childhood. Were the author's name not anywhere on or in the book, the setting  among the Jewish families of Newark in 1944  would be pretty much a giveaway. It's Roth's turf, and he owns it almost aggressively. However, what he's getting up to is not as obvious as it has been hitherto. Lately in his career, it could be broadly summed up by the Rolling Stones' line: "what a drag it is getting old". But here we have something similar to the counter-factual approach in his magnificently terrifying The Plot Against America. Only the threat is more ambiguous, more existential. (It is not lazy association to compare this with Camus' La Peste.) In one early scene, Cantor stands up, one against ten, to a menacing group of Italians, who have come, they say, to give everyone polio; they spit all over the tarmac, and, once Cantor's seen them off, he scrubs the spots clean. But as another character says: "You washed the spit away but you didn't wash the polio away. You can't wash the polio away. You can't see it. It gets in the air and you open your mouth and you breathe it in and the next thing you got the polio." And the character  a hot-dog vendor who himself has been accused of spreading the disease  adds, almost bathetically: "It's got nothing to do with hot dogs."

It is tempting, at this point, to think that there is something allegorical here: that polio is antisemitism, perhaps. But this is too reductive for such a superbly managed novel. It may not be long, but it's full, complete. For one thing, as the above quotation should show you, Roth's ear has never been better, and there is an almost unbelievable mastery of technique in the way that the prose slips between narrative and speech. This is unputdownable, and although it is one of my jobs to show you how authors do this kind of thing, I can't here, except by invoking some kind of magical talent on Roth's part.

I won't tell you what happens, because that might dilute the full effect of the tragedy. (The better a man Cantor is portrayed as, the worse, you come to fear, his fate will be.) Suffice it to say that you know something awful is going to happen. The clue is in the title.

It's the long, hot summer of 1944 in the Weequahic neighbourhood of Newark. Most of the country's young men are engaged overseas, but Bucky Cantor, a muscle-bound, 23-year-old PE instructor, is stuck at home on account of his dodgy eyes. Instead of aiding his nation in the fight against Hitler, his job for the summer is to oversee the welfare of a group of children, as director of one of the city's playgrounds. It's hardly the glorious role he wished for himself, but Bucky, who has a deep sense of honour, approaches his duties  at least at first  with unflagging dedication.

He is powerless to protect his charges, however, against another sinister threat: polio. That summer, in Roth's imagined history, the disease spreads through Newark with nearly as much ferocity as in the (real) epidemic of 1916. Soon, several boys in Bucky's care have died and Roth describes with great pathos Bucky's sombre tasks in the aftermath of these tragedies: the family visits, the consoling speeches to the remaining children in his care.

He expertly captures the climate of fear and hostility the epidemic engenders: suddenly, parents start turning on Bucky, accusing him of hygienic laxness, of letting the children "run around like animals up there". Unsurprisingly, when an escape route presents itself, in the form of a job at the country summer camp where his girlfriend teaches, Bucky takes it, despite admitting to himself that this is a shameful dereliction of his duty.

Roth's 32nd book marks a wonderful return to form after the far-fetched sexual escapades of The Humbling. This is vintage Roth: the story of a good man worn down  and finally ruined  by circumstance. Everything about it is perfectly judged: the way the crisis at home mirrors the larger horrors abroad; the way the epidemic assumes ethnic overtones (the disease is especially rife in the Jewish parts of Newark, prompting antisemitic speculation); the way the climate of fear produced by the polio subtly resonates with our own age's anxieties about terrorism. The writing throughout is flawless and the ending, when it comes, is both clever and profoundly moving.