Books with title Doncia's Demons

Doncia has a secret: She sees weird colours on the walls, and strange creatures like the demon that flies over their tenement at night. But before her inventor father went crazy, leaving Doncia and her mother alone, he gave her a pocketwatch, and by squeezing it she can make the weird visions disappear.When her teacher goes crazy too, the school is closed. To escape the factories Doncia and her friend Piri agree to work in the graf’s castle, where she learns to control the cleaning robots. When she becomes lost in the castle’s underground passages, an impossible flying pufferfish shows her a crumbling rift into a limitless cavern. Can she solve the riddle of her visions before the demon’s sinister purpose tears her life, the castle, and the entire duchy apart?