Herbalist for the Dark Mage

I have to marry, by contract, the strongest dark mage—but I ended up in the house of a warlock who loves candies. He terrifies the servants, and his Darkness lulls me at night. At the gate of his castle there’s an ancient cemetery, and in his study there are living flowers in a fragile vase. My fiancé is the one whose birth date isn’t even recorded in the Book of Life, and I’m an empty—an ordinary human. My family gave a blood oath for our marriage, and I can’t refuse. But will I want a different life once I find out what secrets the territory of the abandoned greenhouse holds—and what is hidden beneath the soulless mask of my fiancé, the most powerful being in this world?