Terror has a new sound.

Young sisters, Sophie and Tennant Riggin, are the only two people to withstand a massive explosion that destroys their community, located in the shadow of Oregon's Mt. Hood.

A team of elite government investigators are sent to research the fallout and the girls - why did only they survive? - but with conflicting objectives. For Dr Martha Chan, a psychologist who analyses large-scale medical emergencies: study them. For Lieutenant Colonel Alexander Fraser, a career military leader with an inherent mistrust of civilians: contain them.

But as the disturbance replicates across the Pacific Northwest, it threatens to topple the chain of command. Dr Chan and Lieutenant Colonel Fraser are caught between the perpetrators of the threat - and those who have the power to resist.