In the closing volume of her thrilling saga, Christelle Dabos transports us back to her wonderful fantasy world. As the walls of mistrust that stood between them lay in ruins, Ophelia and Thorn fall in love. However, they must keep their love a secret and continue their investigation into God's code and the mysterious figure called the Other, and its devastating powers of destruction. But how will they find it, without even knowing what it looks like? More united than ever Ophelia and Thorn arrive at the Deviations Observatory. Here, behind an apparently benign facade, is a laboratory where terrifying, cruel experiments are conducted. Will the lovers discover the truth they've been searching for, and will they be able to bring balance back to the world of the Arcs?