Based on true events in Rio de Janeiro, in 1960, when a gang having the infamous outlaw Tião Medonho as a leader performed a sensational railroad hold-up on a train carrying a small fortune.

Ana, a young psychology student, is hired as a nanny for two children in Petrópolis, Brazil. Left alone with the children and the groundskeeper, she begins to receive threatening phone calls during the night, entering a spiral of panic with tragic consequences.