Monty’s mother, a champion jigsaw-puzzle solver, is worried about him: He claims to be allergic to ghosts, and to be in contact with the ghost of a girl who lives in an abandoned car. So she sends him to the Brinsley Codd School for Sensible Thought, hoping to straighten him out. Monty comes in contact with the ghost of Brinsley Codd himself, and promises to help out by finding former pupils whose lives the teacher is afraid he has ruined by being too nice to them. Mahy (Beaten by a Balloon, 1998, etc.) could have left things there for a triumphantly lighthearted romp—comically illustrated by Staermose—but also intertwines several subplots and minor mysteries, all of which are resolved to the utmost satisfaction of those involved. Along with a crisp pace, an abundance of silly words and silly names, and a cast of children who save the day by showing more sense than the adults can muster, this will please Mahy’s fans, and will also bring her new ones. (Fiction. 8-12)