It's a quest book, with a disappointing result that leaves all sorts of questions you'd been persevering to get answered, unanswered. You know you're in trouble when you come to understand the premise: In the presumably near future, British society has succumbed to crime, debauchery, materialism and violence to such an extent drastic measures are instituted. So far so good! But British subjects are forcibly segregated into four walled-off quarters of the Isles... according to personality.
You have your sanguine quarter, choleric quarter, melancholic quarter and phlegmatic quarter. This preposterous division might actually have been saved by a couple pages' worth about how advances in psychological science -- real or imagined, don't care which -- somehow led to the conclusion that these four ancient "humours" really are very important. Otherwise, Thomson may as well have divided the country by height, or something.
But I don't want to dwell on the premise, about which there are all sorts of things wrong, because the story itself needs to be complained about. Our man, Thomas Parry, ends up illegally flitting from quarter to quarter, trying to... it's hard to say. Well, it's not hard to answer the question from the narrative, but there's no real good reason he's doing all this. Along the way he gets into several sticky spots and scrapes, by goodness, for it is a quest narrative. At one point he's told that by random chance he happens to be an honored guest who can stay, on others' dime, as long as he'd like. How fortunate, in that his money's been destroyed! Only later do you find out that even though he's arrived there by shipwreck (!) from which he's the only survivor, and he convalesces for what must be a few weeks, he's been followed! Dang!
I shouldn't get snippy. Thomson is trying hard, going so far as to bludgeon us over the head with literary devices like having key characters leave impressions in pillows, handprints on windshields, and other traces of themselves where they've been. You recognize it (it's awfully hard to miss) and wonder what might be the reason. Right on schedule, we meet a character who specializes in not leaving traces of herself where she goes and "escaping notice." Wow! I get it! So she's sort of different from everybody else in the book, then?
It's dreadful, until near the end when you think you might be rooting for something to happen, that then doesn't, except the book ends with it maybe about to happen, but by then you don't care because the most preposterous (sorry to reuse the word, but it's perfect) event has just occurred and you're waiting for it to have been a dream or illusion of some sort when you run out of book. Not recommended, if you hadn't gathered.