At Quantico, threats arrive - but in the form of riddles, clues, strange pieces to a puzzle. Maggie O'Dell and her partner Tully make the connection to the weaponized virus and join the killer's game on a scavenger hunt across the country.

As a profiler, Maggie knows that getting inside the mind of a killer always becomes personal. But never like this. Never this bad.

Because now Maggie has been exposed...