Several children on the East Coast are becoming ill and NorBAC must unravel a genetic mystery as fish on a fish farm start exhibiting dangerous, unexpected mutations. The team works on an anti-parasitic drug after tracing the spike in suicide rates in Arkansas. A new looming crisis appears in Washington, as an entire National Guard unit has fallen unconscious and can't be woken up.

After receiving the lethargica antidote Jill and the U.S National Guardsmen seem to be recovering, until the Guardsmen are plagued with a secondary, more deadly infection. Caroline believes her superiors aren't telling her everything about the lethargica outbreak and gets dangerously close to unearthing a conspiracy that may go as deep as the White House.