It is a feature of crime fiction as a genre that a lot of writers are expected to produce a book a year, often featuring the same detective. It’s not surprising that some of these series get a little tired and even the sainted Agatha wasn’t exempt from this. I’ve just read one of her later novels, At Bertram’s Hotel, and, sad to say, it is pretty thin stuff. It was published in 1965, a full forty-five years after her first novel, The Mysterious Affair at Styles. By then Christie herself was 75. Her last novels are really not up to much in comparison with her dazzling prime. That isn’t to say that crime-writers can’t write successfully in old age: look at P. D. James. However P. D. James doesn’t write a novel a year, and other writers who have maintained the quality of their work by letting the time stretch out between books include Martin Cruz Smith and Sue Grafton. I found myself musing on this as I read Ian Rankin’s new novel, Saints of the Shadow Bible. He is one of those writers who does pretty much produce a book a year, but the standard shows no sign of slipping. Exit Music was supposed to be the last Rebus novel, but Rankin did not make the mistake of killing him off, so letting him return from retirement hasn’t been too problematic. It is rather surprising though that Rebus is in such good form, considering the quantities of fags, alcohol and junk he has consumed over the years. Does a vegetable or a piece of fruit never pass his lips? In this novel he finds himself teamed up with the teetotal Malcolm Fox, Rankin’s new series character, who has appeared in two novels of his own. He is am much a straight arrow as Rebus is a maverick. That’s fun, as is the development of Rubus’s friendship with Siobhan Clarke, once his protogee and now his senior. The novel’s intricately plotted, and there’s some terrific dialogue. Perhaps it doesn’t quite reach the heights of Rankin’s best – The Falls is my favourite – it’s still a very good read.