No, this is not pornography or a learned American treatise on the gluteus maximus. The butt is a cigarette butt. The book is a kind of dark if sometimes funny fantasy, but with the realistic elements stronger than in much fantasy. Apparently it’s won a humorous writing prize. I didn’t laugh a lot, but it is very well written.

The story starts with Tom, a middle-aged tourist in an imaginary country, deciding to give up smoking and throwing the butt of his last cigarette from his hotel balcony. Unfortunately it lands on the head of an old bald man below and medical complications follow. It turns out that the old man, though an “Anglo”, had by marriage become a member of a tribe whose traditional law was based on the idea that nothing happens by chance – so whatever ill the old man suffers, Tom is fully responsible.

Will Self is a British columnist on a British paper, so I initially assumed Tom was British, but a few things such as a mention of a “cell phone” in his conversation with his country’s honorary consul made me think he was American. After a while that didn’t seem to quite fit either. Tom is from an English-speaking rich country with a Western culture, but we’re never told which. We’re never told his job either, just some of his family relationships, which include a marriage which seems to be struggling and a withdrawn, computer-game-obsessed son.

The country they’re in is a strange mixture. “Anglos” are one ethnic group among many. The law of the land incorporates various traditional tribal laws. It’s fervently anti-smoking except that some tribes in the hinterland allow smoking. There is an insurgency going on in the hinterland but most people seem to ignore it or take it for granted. It isn’t a realistic land, but if you suppress disbelief in the original premises, things follow quite credibly.

The case against Tom goes on and on. The rest of his family go home. Tom finds himself having to journey into the interior, into the area of the insurgency, to pay reparations, guided by messages from his local lawyer and the honorary consul (neither of whom he trusts), a fellow offender called Prentice and a wordy anthropological tome by a German father and son duo.

Some of the physical description – of scenery, of illness, of squalour – is altogether brilliant. Self also handles descriptions of violent death in a way which emphasises the pointlessness and gracelessness of it. Various strange things happen which make Tom – and the reader – wonder if things are really as they seem. As with a detective story, we start to look for clues to some hidden motif. There is indeed one, and it’s clever and nasty.

I have to stay vague to avoid giving too much away, but the thinking behind the book is strong on philosophy. The politics is totally incredible – some things just wouldn’t work – but I said you needed to suspend disbelief.

The blurb said the book would grip me. It didn’t, though I was interested. I think the reason why I stayed detached was that I couldn’t quite believe either in Tom or in the country he was stuck in. The fantasy fell somewhere between the total fantasy of, say, Gormenghast and a realistic if unlikely thriller. But the bigger problem was Tom. He was a credible character – a little self-centred, mainly well-intentioned, decidedly passive – but I’d have liked to have a real nationality for him, a home, a profession. After all, he has to stay ages in the country and he’s worried about money yet we’re never told if his absence means he’s lost his job. He could have been more grounded and realistic and then his stepping into nightmare would have meant more.