Growing up on Staten Island, filmmakers Joshua Zeman and Barbara Brancaccio were very familiar with the urban legend of "Cropsey." It was understood to be a cautionary tale invented to keep them out of the abandoned buildings of the Willowbrook Mental Institution. Cropsey was said to be an escaped patient who would come out at night and snatch children off the streets. But in 1987, Jennifer Schweiger, a 13-year-old with Down Syndrome, disappeared from their community. For Zeman, Brancaccio, and the other kids of Staten Island, the urban legend suddenly became a reality.