If steampunk as a genre and an aesthetic relies on imagining a late 19th-century world where steam technology never got replaced—along with clockwork cops and airships dotting the skies—then the question needs to be asked: what happens when we roll into the 20th century?

Part of the answer lies in one word: Dieselpunk.

This is not to say that dieselpunk develops chronologically from steampunk but rather that, just as steampunk imagines an alternate version of the 1890s, dieselpunk imagines an alternate version of the period from (roughly) 1920-1950.

This retro-futurism has its own set of tropes: sleek cars from the period with lots of curves and chrome; gritty, dark streets and other elements associated with a film noir aesthetic; imagery and politics connected to World War II; a reliance on diesel power; a dabbling in the occult…and a general sense of existential pessimism.

Imagine The Maltese Falcon’s Sam Spade strapping on a jetpack as he leaves the office, and you’re on your way to imagining a dieselpunk world.

Some have argued that dieselpunk is a corrective to the ideas that surround our collective memory of World War II and the period directly before and after. We often think of that period being defined by a sense of comradery and unity in the face of a crisis, but the dieselpunk world asks us to remember that there was also an undercurrent of disillusionment in the face of those crises–just look at film noir and other artistic expressions from the late 1940s.

In a dieselpunk world, one is likely to encounter a jaded private detective who’s strapped with a laser cannon and a dark sense of purpose. He may be dead by morning, but tonight he’ll try his best to meet his obligations. He’s not the two-fisted American hero who bested the Nazis and is now ready for a life in the suburbs. In a dieselpunk world, those Nazis are probably still lurking in the shadows, and they might have hired a cadre of mages who are looking to conjure the next Reich; they might also have a robot army at their disposal. And the hero or heroine in these worlds is likely to be just a little more like the rest of us…flawed and maybe a little battered but not down for the count.

If you’ve seen films like The Rocketeer or  or any of the Indiana Jones franchise, you’ve dipped your toes into dieselpunk. If you’ve ever looked at an old science fiction pulp and wished the cover could come to life, then you’ve been fantasizing about a dieselpunk world where the jetpacks and laser beams are as real as the grease and the sweat and the menace of real life. And that means you’re ready to dive in just a little deeper.

Welcome to the world of dieselpunk. Your jetpack is waiting.

Ready to dive in? Check out The Blacktop Blues, Book 1 in The Crossover Case Files.