One month after the defeat of a rogue group of terrorists, the United States struggles to maintain control over the New Frontier. The untamed sector of America simmers as opportunists, criminals, and marauders wait to fill the void left behind. An extremist faction of the Navajo Nation called the Rattlesnakes have waited years for this moment. Their leader launches their first, brutal attack on a water treatment and power facility in Colorado.

The message is clear to Colorado Sheriff Lindsey Plymouth and her foreign allies working to keep peace: a new enemy has risen up. Lindsey enlists Raven Spears to track the Rattlesnakes and bring their leader to justice before they can strike again. As the trail gets hot, Raven realizes this is just one of many assaults the Rattlesnakes have planned to conquer the New Frontier.

With violence spilling over the borders, America's foreign allies begin to question the cost to their own forces and start to withdraw. Lindsey and the Colorado Rangers scramble to find new allies, but it will take more than a few friends to hold back the growing Rattlesnake army. If they fail to defeat this new evil, it will devour the New Frontier.