This is like no other book I have read. Twenty four hours in nearly 300 pages reads almost like real-time, which works well in this story of strange neighbours. Each individual incident is plausible, but in combination, it creates an acutely observed surreal nightmare of escalating paranoia.
Earl and Enid are are in their late 40s (but seem older) and long time residents of a quiet road. Their predicable life is overturned by the arrival of new neighbours. Harry and Ramona's unabashed presumptiousness and mind games make Earl lose touch with reality and doubt his sanity: trespass, pointless lies, vandalism and worse.
It's bad enough when strangers are weird and unpleasant, but it is far worse when they are in your own home and when your own family, friends and even random strangers seem to be against you for no reason. And it is relentless, "He believed that she and Harry worked by attrition" so that "Every time he believed he had got things in hand at last, another threat appeared".
At one point, Ramona says "ownership means everything to you" and also asks "how far would you go to avoid humiliation?", which are the crux of the mental assault. This makes Earl behave increasingly out of character, "His persistent conviction that he had been mocked... relieved him of the claims of decency".
No matter how he tries to play it, Earl finds himself wrong-footed by bizarre behaviour and strange non sequiturs. At one point, Ramona has taken over his bed and when challenged, says "It's your house, your bedroom, your bed. What's fair? Do we get any kind of vote?"
One quirk is the overuse of the word "chagrin", even as a verb, "chagrining though it might be"! Nevertheless, it is a painfully realised and expertly written book.
Near the beginning, it mentions that Earl is prone to hallucinations ("he was at odds with humanity as to one of its incontestable truths: seeing is believing"), but it is not mentioned again. So how much of the story is real?