The most shocking secret in the history of mankind is about to be revealed....

A murderer is on the loose on the streets of New York City: nicknamed the Doomsday Killer, he's claimed six victims in just two weeks, and the city is terrified. Even worse, the police are mystified: the victims have nothing in common, defying all profiling, and all that connects them is that each received a sick postcard in the mail before they died - a postcard that announced their date of death.

In desperation, the FBI assigns the case to maverick agent Will Piper, once the most accomplished serial-killing expert in the bureau's history, now on a dissolute spiral to retirement. Battling his own demons, Will is soon drawn back into a world he both loves and hates, determined to catch the killer whatever it takes. But his search takes him in a direction he could never have predicted, uncovering a shocking secret that has been closely guarded for centuries. A secret that once lay buried in an underground library beneath an eighth-century monastery, but which has now been unearthed - with deadly consequences. A select few defend the secret of the library with their lives - and as Will closes in on the truth, they are determined to stop him, at any cost....

Some crimes should never be solved; some secrets are best left buried.