George Poole isn't sure whether his life has reached a turning point or a dead end. At forty-five, he is divorced and childless, with a career that is going nowhere fast. Then, when his father dies suddenly, George stumbles onto a family secret: a sister he never knew existed. A twin named Rosa, raised in Rome by an enigmatic cult. Hoping to find the answers to the missing pieces of his life, George sets out for the ancient city. Once in Rome, he learns from Rosa the enthralling story of their distant ancestor, Regina, an iron-willed genius determined to preserve her family as the empire disintegrates around her. It was Regina who founded the cult, which has mysteriously survived and prospered below the streets of Rome for almost two millennia. The Order, says Rosa, is her real family-- and, even if he doesn't realize it yet, it is George's family, too. When she takes him into the vast underground city that is the Order's secret home, he feels a strong sense of belonging, yet there is something oddly ...