The Invisible Empire is the first of the short series of fast-paced, action-based adventure of Agent 13: The Midnight Avenger, written by Flint Dille and David Marconi in a style reminiscent of popular 1930s pulps. The eponymous title referred to the secret network of operatives working for a sinister organization bent on world domination. After countless years of clandestine activity, the organization exerted inestimable influence in the world, penetrating numerous major governments and powerful institutions.