Adam Gray is a cipher, a disciplined loner conditioned not to betray a single emotion. Part of an elite team spearheaded by a brilliant neuroscientist, Gray is a covert agent armed with PERSONA, a device that allows him to copy the brain patterns of the terrorists and operatives he meets in the field. For twenty-four hours he can recall their memories. He can know every detail of their plans. He can be America's worst enemy--before he's back to being Adam Gray again. Now Gray and his team are racing to stop a plot to release a radioactive isotope that could kill millions.