2197

On 16th January 2197, the Sixth Doctor and Evelyn Smythe materialized on Valiant. There, they discovered that some of its crewmembers were hearing a mysterious bell, just as they had in the TARDIS. They quickly ran afoul of Captain Oswin in trying to investigate the incongruous sound.

The Doctor and Evelyn soon discovered that the ship's cargo hold had a mysterious, ancient door in its cargo hold, which led out into open space. The bell seemed to be a kind of "siren call" which led the crewmembers that heard it through the door and out to their deaths.

Immediately sensing the grave danger this door posed, Captain Oswin sent a distress call back to Earth, but could not hope that backup would arrive any sooner than about two months. (BFA: The Nowhere Place)