Cases of sudden, unexplained deaths—marked by rapid decomposition—are cropping up across the U.S. Their cause: a supermicrobe that causes flesh-eating disease so aggressive that victims die within an hour and infect dozens more.

Suspecting bioterrorists at work, Homeland Security is willing to bend any rule to find the source of the deadly infection, even if it means resurrecting a "dead" Iraqi biochemist, long held in a CIA ghost prison. The disease's unwitting creator risked her life trying to destroy it. Her sister tried, too, and landed in prison. But time is running out as they search for the one person who might hold the key.…