On their honeymoon in St. Augustine, Madison and Tommy expect sunlit shores and quiet nights. Instead, they step into the oldest city in America - and into the grip of a darker branch of The Order, one far older and more dangerous than any they've faced before. Beneath the coquina walls and Spanish ruins, Madison discovers whispers of rituals that predate the nation itself, secrets guarded by shadows that refuse to stay buried. Each clue leads her deeper into a labyrinth of deception, where faith is twisted, vows are broken, and even love may not survive the storm to come. As night falls over the ancient streets, Madison must confront a final reckoning: some sanctuaries protect, while others devour. Haunting, atmospheric, and unrelenting, Sanctum of Shadows brings the Madison Hall trilogy to a chilling and conclusive end.