When a bomb goes off at Yellowstone National Park, threatening the stability of the world's largest active volcano, the reclusive park ranger Harvey "Ben" Bennett is startled to realize that the blast itself wasn't the only threat: the bomb released a virus into the air, and the outbreak is beginning to infect and kill more and more people.

Ben teams up with Juliette Richardson, a driven CDC agent working inside the newly-formed BTR (Biological Threat Research) team, to find the people behind the act of terrorism.

When the attacks get personal, Ben and Julie take it upon themselves to seek out and destroy the threat before it's too late.

A race across the United States, chasing terrorists, dodging bullets, and escaping the threat of a deadly virus outbreak and military apocalypse.