Mechanical engineer Cheng Yan wakes up as Roland Wimbledon, the fourth prince of the medieval kingdom of Graycastle, in a world where the Church hunts witches for their magic. After saving a witch named Anna from execution, Roland starts pairing her abilities with his own engineering knowledge to fortify his backwater territory against monster raids, rival siblings scheming for the throne, and the Church's inquisitors. Recruiting more persecuted witches gives him both allies and a growing target on his back.