After the principal of P.S. 88 gets caught up in a messy spell by one of his students, the other kids rally to help him out.

"The girls are dismayed when their teacher is out sick and they have a substitute. Mr. Z makes goofy jokes and can't keep the class under control. Worst of all, he doesn't say anything when mean Darlene makes fun of Kate and Lucie. Luckily, once the girls turn into dogs, Kate and Lucie learn they can save the day--and even make a new friend"--