Growing up on Staten Island, filmmakers Joshua Zeman and Barbara Brancaccio had often heard the legend of ‘Cropsey.’ For the kids in their neighborhood, Cropsey was the escaped mental patient who lived in the old abandoned Willowbrook Mental Institution, who would come out late at night and snatch children off the streets.

Later as teenagers, the filmmakers assumed Cropsey was just an urban legend. That all changed in the summer of 1987 when a 12-year-old girl disappeared from their community. The police quickly connected this disappearance to several other children who'd gone missing in the area. The hunt for the abductor would lead authorities to the real-life boogeyman living in their midst.