Hounded. Haunted. Hunted. She is the most important person in the world. She is The Key. In the ancient Turkish city of Ruin, American journalist Liv Adamsen lies in an isolation ward staring at walls as blank as her memory. She knows she entered the monumental Citadel at the heart of Ruin but can remember only darkness. Something strange is stirring within her, whispering that she is 'the key'. But the key to what? For the Ghost, a mercenary operating in the Syrian Desert, Liv could unlock one of mankind's most potent secrets. For the brotherhood in the Citadel -- now cursed by a terrible plague -- her may be the only way to ensure their survival. And for a powerful faction in Rome, she threatens the very future of the Catholic Church. Hunted across continents and caught up in events that defy explanation, Liv turns to the only person she trusts -- a charity worker named Gabriel Mann. Together their paths lead to a shocking discovery -- one that will tear them apart and change the world forever!