Dennis Wheatley, who also wrote history and political analysis, was called "Prince of Thriller Writers" by a critic in the Times Literary Supplement (8 June 1940), and this motto was emblazoned on the spines of the collected edition of his works. In his lifetime he published more than sixty volumes of fiction, principally in the fields of adventure, espionage, and historical romance. They sold over twenty million copies. The majority of them are long, three hundred to four hundred pages, for he believed in giving the reader his money's worth.

Wheatley's works of fiction can be divided into six categories: four sets of books with continuing characters (the Duke de Richleau, Gregory Sallust, Julian Day, and Roger Brook), plus stories of black magic and straight adventure novels. The hero of each series was developed to exist in his own world, as though the books in that series formed his official...