When he lends a young teenager books from the Unshelved — which contains such terrifying works as Lady Chatterley's Lover, Nineteen Eighty Four and The Hite Report — he doesn't realise that she is the daughter of a local politician, or that she is about to go missing. Though Israel endures a dawn visit from the bumbling local police and is blackmailed into investigating the disappearance by the glamorous journalist of the local rag, this "mystery" never goes anywhere. No one dies, there's no tension or suspense, and the whole thing is wrapped up at the end without any fuss, almost in passing.
This feeble excuse for a plot is just an opportunity for Israel to encounter a range of characters in different social settings. The farming family he lodges with, fallen on hard times. The Eastern European migrant workers in the local fish and chip shop. The denizens of the Internet gaming parlour. The Presbyterian minister, whose concerns about prevenience and knowledge of Hebrew aren't helping him deal with a breakaway youth revival movement. A Fish and Chip Biblical Quiz Night, which leaves the secular Israel completely floundering. The old Anglo-Irish aesthete who is one of his few friends. His boss, who is on his case to fill in the Self-Assessment Questionnaires for his job as "Learning Support Facilitator". And more.
All of that gives something of a feel for small town life in Northern Ireland, but this is incidental to the entertainment. Sansom's is a gentle humour, in which people's foibles and eccentricities and failings provide amusement but are ultimately accepted. The Bad Book Affair is one book in a "Mobile Library" series, but it worked perfectly well by itself and I recommend it for anyone after an entirely unthreatening social comedy.