Private Investigator Theo Nikonos is back. Having been acquitted of a double murder charge, the paranormal detective has left New York and is spending time in Spain, recuperating from his harrowing experience—and recovering from the loss of the woman he loved.

A chance encounter with a mysterious young nun, known only as La Magdalena, turns Theo's vacation into an investigation that unearths the little-known and mysterious world of early Christianity. A conversation with a priest, who tells a story that is stunning in its scope and heretical in its context, turns deadly. Theo realizes that there is someone who will do anything to prevent the revelation of who La Magdalena really is. And who she is will shatter the foundation of the Christian world.