On a field trip, Susan Piper takes her class to The Wellington Mansion and tells them how it was haunted before she got rid of the ghosts a decade ago on Halloween with her friends' help. She also told her class how to re-haunt the house and warned them not to do so. The next day, on Halloween, six of Susan's students enter the mansion, bring the ghosts and monsters back, and get scared out of their wits. Jack, the jack-o-lantern who knew their teacher, protects them with help from Alvin, the ghost puppy, and tries to convince Victoria to read the same spell Susan read when she was in the mansion to get rid of the ghosts.