Art restorer and sometime spy Gabriel Allon is sent to Vienna to discover the truth behind a bombing which killed an old friend, but while there he encounters something that turns his world upside down. It is a face - a face that feels hauntingly familiar, chills him to the bone and sends him on an urgent hunt for a name, a history, a connection. Each fact he discovers only leads to more questions: each layer he strips away revals more layers beneath. Finally, a picture begins to emerge, but one more terrible than he could have imagined, a portrait of evil stretching across sixty years and thousands of lives and into his own personal nightmares. Soon the quest for one monster becomes the quest for many.