Captain Mark Stephens was overseeing the change of shifts at the state of Illinois' maximum-security prison when the world outside was suddenly ripped. They thought it was an earthquake until they found that the Mississippi river had disappeared, along with all signs of civilization. Then the sun came up—in the wrong direction. And a dinosaur came by and scratched its hide against the wall of the prison... Something had thrown the prison back in time millions of years. And they were not alone. Other humans from periods centuries, even millennia apart had also been dropped into the same time. Including a band of murderous conquistadores. But the prison had its own large population of murderers. They couldn't be turned loose, but what else could be done with them? Death walked outside the walls, human savagery was planning to break loose inside, and Stephens and the other men and women of the prison's staff were trapped in the middle.

The time-twisting Assiti Shards are the distressing consequences of a highly advanced and completely insane alien race's idea of art. One of the shards has struck in southern Illinois region, thrusting peoples from different historical eras into the middle of one of the most dangerous periods ever The Cretaceous! Lost in a nightmare world, a conquistador from the year 1541 finds a U.S. Cavalry Scout from 1838 hanging helplessly from a snare. The Spaniard frees him, an act of mercy leading to an uneasy alliance. After battling a 'dragon' we know as the Tyrannosaurus Rex, they find themselves in the shadows of the Cyclopean pyramids of Cahokia, the greatest city of the forgotten Mississippian civilization. The Rattlesnake Priests prepare a grisly celebration for their reptilian god, but thanks to the intervention of the Raven Priestess, they escape the city with a pair of Pre-Mound tribesmen who invite the castaways from the future to join them in their beleaguered village. They find the villagers trying to defend themselves from the giant creatures roaming this primeval land. Thankfully, a new hope can be seen across the vast, dry flats of the Drained Sea—a mysterious mesa rising more than a thousand feet into the sky, another bizarre result of the unnatural disaster Could this be a haven? To find out, the four newfound friends set out on a journey that will prove to be more dangerous than anything they have faced yet!

The unlikely foursome of an AWOL US cavalry scout, a repentant conquistador, and two young chiefs of a neolithic pre-mounds tribe have formed a friendship and alliance that breaks the bonds of centuries and cultures. They are now the 'dragon'-slaying four Great Chiefs of the young Mesa Peoples and Allied Tribes, a human civilization growing against steep odds in the Earth's Cretaceous Period (introduced in Time Spike: The Mysterious Mesa). These bold heroes now face a formidable foe, not the enormous dinosaurs that roam this ancient world, but other humans! The rapacious Rattlesnake Cult from the City of the Pyramids has laid siege to Stone Wall Village. Only the newly-minted First Cavalry of the Cretaceous, brave pre-mounds warriors astride a prehistoric equine species native to Pleistocene North America have a chance of saving their kinfolk and restoring peace and prosperity in the lush and deadly New New World. Here comes the cavalry!