Furst’s heroes are almost never British or American, which means they come from countries that have been or will be conquered. They are all Continentals, living in an age when Britain was not imagined to be part of the Continent, and in a geographical (and perhaps other senses), wasn’t, as the Third Reich would pretty swiftly discover. A contemporary dictionary tersely defined a sea lion, as Peter Fleming wittily observed, as a carnivore very imperfectly adapted to a marine environment, and that imperfect adaptation meant that Britons and Americans were spared certain choices history forced on Continentals. Most of Furst’s novels celebrate the ones who made an extraordinarily difficult choice.

The Spies of Warsaw, the first novel in the series not to do that, does something else: it reminds its readers fact that while intelligence services can succeed in gathering the facts, military and political elites can refuse to break with their preconceptions, and that if men and women are sufficiently unlucky, truly ghastly things will follow.

May of 1940 remains an infinitely compelling moment because it reminds posterity that military innovation can alter the course of history, allowing the new and monstrous to overthrow the normal and civilized. In this sense, Furst’s tenth book describes the origins of the books that preceded it: it describes how Continentals became so unlucky that they needed heroes.