[2] In the film, Marnie persuades the Halloweentown Council to allow magical students to attend a mortal school, but risks losing her family's powers if something goes wrong before midnight on Halloween.

Marnie, regretting what she said to the council, wants to cancel the program she has made, but her grandmother Aggie opposes, saying that they have nothing to fear.

Marnie gradually encourages the students to join sports teams, school activities, and to make new friends.

Meanwhile, Marnie's developing relationship with Cody parallels an unexpected romance beginning between Aggie and the school's principal Phil Flanagan.

At the school carnival, Dalloway launches magical attacks against the mortal students by bringing the inanimate monsters in the haunted house to life.

Dalloway claims the Cromwell magic and explains that his son Ethan helped with most of the things that happened, but Gwen has shown the evening's events to the Halloweentown High Council.

Brown was more involved in the storyline of Halloweentown High and provided some input into the script to ensure continuity across the films.

They noted that, although the film spends limited time in Halloweentown, the portrayal of Marnie navigating high school proves engaging.

They appreciated the film's combination of cheesy high school elements with supernatural themes, noting that it felt tailor-made for their tastes.

Rhett concluded that Halloweentown High is a fun and entertaining Halloween film with valuable social commentary.

Furthermore, Robledo remarked that while tweens are unlikely to be frightened by the somewhat rudimentary special effects, younger children might find them unsettling.