A disease called the rot has spread to the United States, leading to a quarantine being imposed on most of California. Victims react in different ways. Most become like zombies, wandering about aimlessly unless they come across someone to bite and spread the disease. Others become aggressive and animal like. Rarer are those who seem to immune. Eric Vance of the newly formed Tactical Medical Response Team is one of the immune. He is trapped in San Francisco awaiting rescue after a doomed mission into the Quarantined California left him and two others stranded. He learns his ex wife, Donna and teenage daughter, Katelin are trapped in a newly quarantine part of Southern California. Knowing they are trouble he makes plans to leave his post and go help them. Donna and Katelin are not waiting around for help. They fall in with a motley bunch of survivors and try to fight their way out, but the rot is much more pervasive and deadly than they could have anticipated. To complicate matters roaming the wasteland collecting the immune and processing them into samples to study is mad TMRT scientist Dr. Talbot. Even if Vance and his family can survive the rot Talbot has other sinister plans for them.

Eric Vance has managed to reach his ex-wife and daughter while avoiding hordes of the infected and a rogue scientist. However, they are still stuck in the quarantine zone. Trapped among the victims of the rot, a deadly disease turning its victims into either mindless zombies or ruthless predators, both seeking to spread the disease. He takes his family and other survivors they have met along the way to an old army buddy turned survivalist’s who has fashioned a homemade underground bunker. They hope Vance’s paranoid friend may have a way out of the quarantine zone, but even the man preparing for the end of the world was not prepared for the rot.

The Vance family and their rag tag group of survivors find temporary refuge in the home of Mrs. Rutherford, a straggler who stayed behind to care for her invalid father. With the rot having turned just about the entire town into either cunning predators or mindless, but hungry for the flesh of uninfected, zombies, they know they won’t be safe anywhere long. Given some time to regroup, however, they come up with a workable plan to get out of the Quarantine Zone. What they don’t know is a new even deadlier version of the already dangerous rot is on its way to make things even more difficult.

Eric Vance and his group themselves in the compound of conspiracy driven radio show host Cam Carson. Knowing nowhere is safe for long, half the group agrees to help a mysterious foreign agent stop a misguided plan to set off nuclear weapons in the Quarantine Zone in exchange for helping them escape rot infected Southern California. As dangerous as venturing out of the compound is, the rest staying behind the wall with Carson and his militia are in the crosshairs of a new breed of the already cunning vampire rotters. While the group keeps looking for a way out the Quarantine Zone keeps growing as the new strain finds ways to continue the spread of the rot to new previously safe areas.