They Is Us, By Tama Janowitz

If the import of this book's grammatically dubious title has passed you by, consult the blurb. "This is not America as it is," it explains, but "America as it could be", in a future split between rich and poor, where the rich live in Eden, the poor in a toxic suburbia.

THEY is US, is the point, in a phrase of exactly the kind of reductive pointedness that will make any satire, no matter how ingeniously built, clunk like an old washing machine. Janowitz is a queasily imaginative author, and They Is Us draws a lot of strength from the energy of her sentences, and the fierceness of her wit. But her novel sometimes feels as if she might have written the blurb's claim that this fictional world is "not all that different to today" on an index card and stuck it behind her desk, lest the book should be torn from that narrow purpose by anything like a life of its own.

The holding-up of the mirror begins in New Jersey, a promising hunting ground for a dystopia. We're in the not-so-distant future, a time when Gwen Stefani and Busta Rhymes are considered early-modern classical music. The dystopic bit is neatly summarised in a map of the US drawn by Julie Fockinoff, a student at Robert Downey Jr. Junior High, and a member of the wearily dysfunctional and slightly mutated family upon which the book is centred.

Julie's diagram shows a nation missing swathes of its West Coast, lost in a mysterious natural disaster. What remains is split into a radioactive urban wasteland, a climate-changed wilderness, and a vast leafy idyll reserved for the oligarchs of the future. That's the setting; the plot, such as it is, is basically a series of excuses to drift around this world in search of minor entertainments, from grotesquely genetically-modified pigs to a school system that has resorted to teaching its illiterate charges everything on the Product Testing and Hair Styling syllabus by means of hologram television alone.

The best joke comes in a throwaway mention of security alerts, which have been subtly rebranded from red and orange to soothing lime and lavender. These baroque and thoroughly imagined features ensure that They Is Us is never less than a lively read. It's when Janowitz attempts more sustained parallels that the reader loses heart.

Partly, the problem is one of tone, which is too repetitively shrill to prompt the kind of vigorous head-nodding that effective satire ought; partly, it's to do with timing. Publishing lead-times do make it difficult for a book to feel bang up-to-date. But much of this novel deals with the homeland security paranoias of Bush's administration, and it wouldn't have been hard to figure out that such a subject might be old hat in 2009.

This isn't to suggest that a new presidential era has brought a wider cultural change. But in her future President Wesley, Janowitz has presented us with such a specific and nightmarish Bush analogue – who spends most of his time on shopping TV, urging the public to call in at ten dollars a pop and decide which country should be next to become a "Safe Democratic Homeland" – that it's impossible not to feel the whole endeavour is a little dated.

The curious result, for most of this book's probable audience, is to be left in the frustrating position of agreeing with the most simplistic point of view in the argument. When satire expires, it just begins to sound like bitterness.