Growing up on Staten Island, filmmakers Joshua Zeman and Barbara Brancaccio had often heard the urban legend of "Cropsey." It was a cautionary tale invented to keep them out of the abandoned buildings that remained of the Willowbrook Mental Institution. Cropsey was supposedly an escaped patient who would come out late at night and snatch children off the streetssometimes with a hook for a hand, other times with a bloody ax. 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, their urban legend became real.