Hexwood (2002) Paperback Book - (Diana Wynne Jones)

From her window, Ann Stavely watches person after person disappear through the farm's gate -- and never come out again. Later, in the woods nearby, she meets a tormented sorcerer, who seems to have arisen from a centuries-long sleep. But Ann knows she saw him enter the farm just that morning. Meanwhile, time keeps shifting in the woods, where a small boy -- or perhaps a teenager -- has encountered a robot and a dragon. Long before the end of their adventure, the strangeness of Hexwood has spread from Earth right out to the center of the galaxy.