In the magical town of Roseyville, where a witch controls the activity of a nearby volcano, Mitzi, a headstrong high school senior, believes her ticket out of the small town is to become a professional basketball star. The championship game is in two days, and to guarantee her success, Mitzi has been learning telekinetic magic from the local witch, Tarantella. Mitzi’s lessons with Tarantella are going well and it looks like she’ll be able to win the championship, but just as Mitzi’s about to master magic, Tarantella disappears without a trace. Mitzi finds out Tarantella has gone to Sunset City to help her true love Jagger, the Head of Town Council, who has tragically become addicted to the illegal drug sugar.
Mitzi recruits her cousin Merryn, a gumshoe do-gooder, to accompany her to Sunset City to track down the witch. They discover that she has gone to the city’s mayor, Belanos, for help, but Belanos is not what he seems. He purposefully got Jagger hooked on sugar so that he would eventually seek refuge in the city. Belanos also knew the witch would leave Roseyville for Jagger, thus putting the town in danger. Belanos wants Roseyville to be destroyed by the volcano so that Sunset City can annex the land and extract its resources. With the witch gone, The volcano rumbles with seismic activity. The basketball championship will be canceled if the volcano doesn’t stop quaking.
The only people who have access to Belanos’ building are guests at a fundraising gala. Lucky for Mitzi and Merryn, they know someone, Lamar, who has a ticket. Mitzi bets Lamar that she can beat him at basketball in exchange for his ticket to the gala. She uses magic to cheat at the game. The volcano begins to erupt. It’s not just the championship that is at risk, but now the whole town could be destroyed! Mitzi goes to the gala while Merryn returns to Roseyville to warn the townsfolk that the volcano is going to demolish everything. Tarantella uses her magic to infiltrate the building and locate Jagger. While at the gala, she spots Mitzi and they make a plan to return to Roseyville. But Belanos is one step ahead of them. He sends his assistant to get Jagger and take him to the city’s underworld where he commits himself to sugar forever.
When Belanos tells Mitzi and Tarantella about what has happened to Jagger, the witch goes on a rampage and destroys several blocks of the city and then follows Jagger into the underworld, abandoning Mitzi. The only way left to save Roseyville is for Mitzi to become the new witch, and cast her own protective spells, thus sacrificing her future in basketball. She returns to her hometown and saves it from the volcano, but ends up stuck in Roseyville as an outcast.