Poppy Pym And The Double Jinx

From the Winner of the Scholastic Montegrappa Prize for New Children's
Writing

It's Halloween at Saint Smithen's. When the Brimwell town hall burns
down, the amateur production of Macbeth is moved to the school
and it's all hands on deck. But when the play is struck by a series
of mysterious attacks, it's up to Poppy, her friends and her
circus family to save the play and unmask the culprit.