The story for Cadillacs and Dinosaurs starts with Earth being heavily polluted and suffering from a series of huge natural disasters which have destroyed cities and killed millions. In order to survive, humans across the world build underground cities and soon enough, everyone is living underground. n600 years pass since humans first built their underground cities, and it is decided that people should return to the surface and see what is out there. They do so, only to find...dinosaurs! These thought to be extinct species were back, along with other monsters, and were freely roaming the Earth. This doesn't put off some humans though, who soon start to return to the surface.

The dinosaurs seem to be quite a bit nicer than before though (judging from how the intro claims they "rarely attack people") and humans seem to be able to get along with them pretty well. But there is a group of humans known as the "Black Marketeers" who hunt out and kill the dinosaurs in order to make money. The dinosaurs are getting angry and have started to attack anything they see. What's causing this?

So in step Jack Tenrec, Hannah Dundee, Mustapha Cairo and Mess O'Bradovich, ready to take on the Black marketers and destroy the gang and their mysterious leader, Fessenden.