Mill Valley, Pennsylvania, Halloween night, 1968. After playing a joke on a school bully, Sarah and her friends decide to sneak into a supposedly haunted house that once belonged to the powerful Bellows family, unleashing dark forces that they will be unable to control.
In a gritty and alternate 1985 the glory days of costumed vigilantes have been brought to a close by a government crackdown, but after one of the masked veterans is brutally murdered an investigation into the killer is initiated. The reunited heroes set out to prevent their own destruction, but in doing so uncover a sinister plot that puts all of humanity in grave danger.