Edinburgh, 2001. Immersed in a secret investigation that is consuming him, Rust Fraser lives his days between obsession, guilt, and the certainty that his doom is loneliness. In the same city, Agnes White survives in the darkness of her mind, trying to discern what is real from what is not. When Rust meets Agnes, he sees in her all the answers he needs to move forward with his investigation. When Agnes meets Rust, a small flame of hope ignites in the darkness that surrounds her, leading her to believe that perhaps, after all, she is not crazy. As their paths intertwine, Agnes and Rust will unearth one of the best-kept mysteries of Western society. They call them Sanctas. According to some, they are the salvation of faith. According to others, a threat capable of destroying everything. Destroying them. Perhaps there are secrets they should never have revealed. Perhaps time is running out. Perhaps it would have been better to never have met.