The Obscura
The Obscura was a fracture in spacetime, which caused death if a person looked directly into it.
A single soldier was recovered from the fracture, who produced the only guide to navigating it. Though the Obscura was widely believed to have been created in one of the Time Wars of the Time Lords’ ancient past, Irving Braxiatel learnt from the soldier that he actually came from a Time War yet to come.
A Time Lord research station was set up around the Obscura to monitor it. Danna was stationed there by Braxiatel. Many centuries later, Braxiatel returned with Ace to see if there was a way of using the Obscura's power as a weapon. Learning that there was a Dalek ship nearby, Braxiatel made them aware of their location with the promise of passing on Gallifreyan weapons to them. This was a lie and he opened the station's protective barriers, causing the Obscura's energies to destroy the Daleks.
However, the Daleks had exterminated Danna and Ace was almost killed by the Obscura's energies, so Braxiatel left with her, intending to wipe her memories of the Last Great Time War and Gallifrey. (AUDIO: Soldier Obscura [+]Loading...["Soldier Obscura (audio story)"])
The Nightjar passed the Obscura and survived it dangers during its journey. (AUDIO: Pursuit of the Nightjar [+]Loading...["Pursuit of the Nightjar (audio story)"])