Enigma for the Devil

After the death of her father in Argentina, Elza returns to Brazil to visit her remaining family. While visiting her mother's grave, she takes a flower off an unknown grave and puts it in her mother's. Soon after that, she begins to receive strange phone calls from an unknown voice saying: "Give back my flower!". She becomes terrified and obsessed with the stranger's voice, and starts believing that it's the spirit of the deceased.