Plot

A teenage girl, who accidentally releases an ancient and mischievous spirit on Halloween which causes decorations to come alive and wreak havoc, must team up with the last person she'd want to in order to save their town - her father!

When the Gordon family moves from Brooklyn to a small town called Bridge Hollow, the town's obsession with Halloween fascinates daughter Syd and disgusts her scientist father, Howard. Syd meets her new school's Paranormal Society, who inform Syd that her family's new house is believed to be haunted.

Despite Howard's contempt for Halloween, his wife Emily makes vegan snacks for the local Stingy Jack festival and Syd puts up Halloween decorations. When Syd lights the lantern she found, the family's Halloween decorations come to life and fly away. Syd learns that the descendant of the woman who died in the house is still alive and elderly in a nursing home, and she takes Howard to discuss the lantern with the woman, who tells them that when lit, it releases Stingy Jack, who will take a soul at midnight to take his place.

Syd meets up with the Paranormal Society at her school and explains what happened; while there, the group find out that a resident of their town has a page torn from a spell book that could help them re-trap Jack inside of the lantern. They go to the address of the person who has the page only to find it is their school principal. After fighting off more of Stingy Jack's minions, the group goes to a crypt to find the incantation for the spell from the original owner of the spell book: the ghost who haunts Syd's new house.

While the Paranormal Society and the principal go to the town square to stop the Halloween decorations from attacking the town, Syd and Howard realize that Emily has left the festival and is at home with the lantern, and go back to their house to return Stingy Jack to his lantern. Stingy Jack threatens Emily, mistaking her for the one who found his lantern and the one whose soul should take his place. Howard attempts the incantation to bind Jack several times as he tries to take Emily away, but Syd reminds him he has to believe in it for it to work, and after Howard says the incantation while believing, Jack is banished again, and all the other Halloween decorations fall down, inanimate again.

After what they've gone through, Howard becomes more accepting of Halloween, Syd joins the Paranormal Society, and Emily begins to bake treats that aren't vegan, claiming "you only live once".