On 16 January 2197, the crew of the Valiant, a fighter-carrier just passing by Pluto, began hearing bells. First came Armstrong, who went mad from the incident and was drawn to a door: an impossible door that lead nowhere. The Sixth Doctor and Evelyn Smythe, having just materialised on board, quickly ran afoul of Captain Tanya Oswin while trying to investigate the incongruous sound.
The Doctor and Evelyn soon discovered that the mysterious, ancient door in the ship's cargo hold apparently led into open space. The bell seemed to be a kind of "siren call" which led crew members who heard it through the door and to their deaths. Over time, more and more of the crew began hearing the sound and acting accordingly.
Realising the grave danger this door posed, Captain Oswin sent a distress call to Earth, but did not hope that backup would arrive any sooner than March. The Doctor, tracing the sound to 7 September 1952, went there to investigate with Oswin's permission, promising to return. (AUDIO: The Nowhere Place)
On the same day in 1692, when questioned by her uncle, Reverend Samuel Parris, Abigail Williams accused "Susan Chesterton" of attempting to entice her into witchcraft. When the First Doctor, Susan, Ian Chesterton and Barbara Wright went into the forest — thought to be the abode of the Devil — to reach the TARDIS, Parris followed. (PROSE: The Witch Hunters)