She was a painting by Titian; she was queen of the Holy Roman Empire, and 500 years ago an audacious sisterhood buried a secret in her name.

Lisbon 2020: a pair of forensic archaeologists discover a strange skull buried with the original occupant inside a fifteenth-century tomb. That same night, one archaeologist is murdered and the skull stolen, leaving the surviving archaeologist to dispatch a plea for help. Enter Phoebe McCabe and the Agency of the Ancient Lost and Found, now assigned to help a headless client become reunited with his skull. Yet, why would anyone steal a centuries-old cranium in the first place?

But the unfolding truth is more baffling than anyone could have imagined. The missing skull may hold the key to centuries of European intrigue, religious fanaticism, and political upheaval. As Phoebe digs, layers of royal plots emerge, along with tales of persecution and an underground resurgence of a brotherhood so virulent that it threatens the world to this very day. Yet, even in the fifteenth century, the sect had its enemies, and Phoebe needs to find the clues those long-dead allies left behind. For that, she must look in surprising places.

As she races to locate the skull she calls on instinct, intuition, art, and the help of an ancient sisterhood. Somewhere in the past lies the key to save the future and it will take every resource Phoebe possesses to pull the pieces together in time.

From the misty forests of Portugal to the castle promontories of Spain, Phoebe is pitched against a breed of fanatic it will take all her skill to beat.