The poisoner’s handbook?

The only objective of a writer, said the critic Cyril Connolly, is to write a masterpiece. This is nonsense, of course, unless it is made true by definition: that no writer who does not aim at one is really a writer. Nevertheless it is undeniable that most writers would prefer to have written a masterpiece than not to have written one, in which case Anthony Berkeley Cox (1893-1971) ought to have died fulfilled—though almost certainly he did not, for he wrote no fiction for the last 32 years of his life.

His masterpiece, published in 1931 under the pseudonym Francis Iles, was Malice Aforethought. The hero of this book, or perhaps I should say protagonist, is a …