Unless I have drastically misunderstood his latest novel, I’m forced to conclude that, in his ninth decade, Norman Mailer has completely dropped his conkers. The Castle in the Forest is a preposterous book; a bafflingly preposterous book. It is, at least ostensibly, trying to tell us something about Adolf Hitler. But what on earth is it trying to tell us about him?

As it opens, its narrator introduces himself as ‘DT’, short for Dieter – a former member of an elite SS Intelligence group under the supervision of Heinrich Himmler. Himmler, Dieter tells us, is obsessed by incest. Himmler thinks that, as well as magnifying and exacerbating congenital defects in the products