2197

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 two months. The Doctor, tracing the sound to 7 September 1952, went there to investigate with Oswin's permission, promising to return.
Over the next two months, thousands of the crew had fallen victim to the bells, going to the door even though it was at that point in open space. In March, the Doctor and Evelyn returned. The Doctor covered the entrance to the door, and dematerialised, bringing the portal door with it. Meanwhile, Captain Oswin ordered missiles to be launched at the location where the door had been. The remaining crew evacuated, but Evelyn stayed behind out of faith for her friend. The Doctor, after visiting "Time's End" with Hayman, changed the coordinates of his ship so that the missiles would destroy it circa 50,000,000,000 BC. The Doctor and Evelyn, having saved humanity from one of its predecessors, departed. (AUDIO: The Nowhere Place)