Mildred Hubble returns to Miss Cackle's Academy for Witches with a big dream: to be chosen as Head Girl! But with Mildred's history of mistakes and mishaps, even her best friends are skeptical. Besides, Mildred's rival, Ethel Hallow, is sure to win. Still, the new term is going well until Ethel finds out that Mildred's beloved stray dog, Star, actually comes from a traveling circus, and Mildred is forced to return him. When Mildred realizes just how unhappy Star and the other circus animals are, she's determined to get Star back and give his companions a better life, even if it means the headmistress won't pick her for Head Girl. Little does she know that friendship, compassion, and loyalty might be just the qualities Miss Cackle is looking for!