End game

the long version

"Langley is experiencing a series of gruesome murders. The CIA's own headquarters should be the safest spot on the planet, but a highly professional, violently psychopathic assassin, who hideously disfigures his victims, strikes without mercy. The murders spread from Langley to a prison outside of Athens, where the first clue to what will become the End Game surfaces. A code carved into four copper panels of the legendary statue in a courtyard at CIA headquarters, known as Kryptos, predicts the means and the terrible necessity for the serial killings"--Amazon.com.