The veil

Deep in the Ministry of Magic’s Department of Mysteries was a chamber devoted to the study of Death - a large echoing room that had a great stone pit at its centre. Within that pit, on a stone dais, was the Veil. A tattered black cloth that seemed to gently flutter, the Veil was a mysterious barrier between the lands of the living and the dead. Although the air around it was silent, still voices could be heard from it, potentially the voices of those that have passed on, just on the other side.

However, once a living person had passed through the Veil - there was no return.