Ardethe

Ardethe was a planet in the constellation Kasterborous. It was the seventh in its ten planet system and was entirely covered in blue rocks. It had a great secret protected by the Knights of Jeneve, who would instead give hopeful travellers the coordinates of a mysterious planet where they had built a bobby-trapped replica of Emmanuel College in Cambridge. (PROSE: Deadfall)

The Mother and Father of the Shadow Spire saw campfires of "ritual and bone" hiding in Homeworld ruins on Ardethe. (PROSE: The Story So Far...)

Behind the scenes
Ardethe's three moons are named after the original members of : (Keren) Woodward, (Sarah) Dallin and (Siobhan) Fahey.

In the original unlicensed Audio Visuals version of Deadfall, where Ardethe was first introduced, it was Gallifrey after the Time Lords were destroyed by the Daleks in Planet of Lies. There are still hints of this in the novel, such as the "Shabooj'm" who inhabit its ruins. Ardethe was eventually confirmed to be the ruin of one of the Nine Homeworlds through an offhand mention in the Faction Paradox short story The Story So Far....

The destruction of "Fred's homeworld", as seen in Planet of Lies, was also mentioned in the 2021 novelisation of Cyber-Hunt, where Fred makes a deal with the man in black to have it undone. Fred successfully fulfills his part of the bargain and severs Fred from his original history as the price to pay for erasing his homeworld's destruction from time, leaving behind an amnesiac Fred who has been untethered from his former identity, now occupied by a different man. As a result, a possible interpretation is that the ruined Ardethe of Deadfall is the planetary equivalent of Fred, the "ghost" of a ruined Gallifrey that now never was, existing separately from the "real" Gallifrey. However, only the context of the unlicensed Audio Visuals ties Fred's destroyed homeworld to the planet seen in Deadfall and The Story So Far….