Sedu is a barren Frontier World within the Jericho Reach's Slinnar Drift that serves as an independent waystation for underworld and criminal activities among Humans and many other intelligent species active in the Reach.
It is the only world in the Slinnar Drift known to be inhabited.
Those Navigators who have travelled the near reaches of the Silent Road claim that Sedu occupies an important astrographics nodal point along its route and that it is located at the very juncture of equal and opposing forces.
The Warp leading to Sedu is subject to the usual, albeit unpredictable, perils, while beyond it, the otherworldly quietude of the Silent Road prevails.
Some claim that Sedu must therefore represent some as-yet unused gateway, while others liken it to a victory arch of old, the likes of which ancient armies would pass on their return from conquering some far land.
When isolation and stagnation befell each world of the sector, Sedu suffered some doom not recorded by the galaxy at large. When leading elements of the Achilus Crusade attempted to make contact with its people, they found a world that appeared to have undergone a drastic transformation.
One savant seconded from the Ordo Xenos claimed that Sedu had been sucked dry by something that had awakened deep within the Slinnar Drift, like a living sacrifice made to some slumbering outer god, or a paralysed prey creature left near an egg by a mother that knew it would not be alive to see its offspring hatch.
Those forces despatched to investigate found only scattered tribes of Feral Orks and the occasional band of devolved mutants wandering the deep wastes. Needless to say, Sedu is of little interest to the Achilus Crusade, in an official capacity at least.
In an unofficial manner, Sedu is very important indeed. As the only life-sustaining world within the Slinnar Drift, it serves as a jumping-off point for those heading into its lambent depths. While the Imperium believes the place to be unoccupied by Humans, this is far from the case.
All manner of recidivists, outcasts and xenophiles call Sedu their home, for a time at least, the world serving as neutral ground to a number of equally reviled factions. A number of very well-hidden settlements have sprung up of late, while a number have probably existed since the Age of Shadow, each of them host to a wide range of underworld scum.
Cold Traders are known to ply their wares in subterranean markets, prospective purchasers of xenos-crafted weapons and objects des arts clamouring to bid for items whose ownership would see them burned on the pyre on any world in the Imperium.
Slaves of all intelligent species are driven to concealed fleshmarkets, paraded before those who would purchase Humans and aliens for a range of uses, many of them cruel or violent.
Very few of those who attend such events acknowledge the Throne of Terra, and it is said that all manner of xenos are suffered to co-exist alongside the remnants of Humanity that infest the place, a fragile peace existing between them, at least as long as it takes to conduct their vile business.
It is one such place that represents another of the mysteries of the outer Jericho Reach, though very few are even vaguely aware of its existence. The greatest of the hidden settlements of Sedu is a subterranean city known as Rosenman's Refuge, a warren of caves and tunnels within a huge mesa.
Though its existence is known only to the city's rulers -- a group called "the Council" -- a huge relic of obviously xenos manufacture lies at the heart of Rosenman's Refuge.
This relic is thirty metres in diameter and takes the form of a disc of dull metal, which pulses with a sanguinary illumination each time a vessel translates from the Warp in the vicinity of the planet.
Key members of the Council attend the device at all times, treating it as if it was some sentient oracle blessing them with foreknowledge of the approach of enemies.
The existence of the xenos device is as yet unknown to the Deathwatch, though it has actually been witnessed by several agents of the Holy Ordos who were uncovered by the Council attempting to infiltrate their city and interfere with the trade that provides their wealth.
Several of these agents were sacrifices to the Council's alien oracle, as punishment, as well as to appease the alien thing and to ensure it continues to warn the Sedu underworld of external threats.
- Deathwatch: The Outer Reach (RPG), pg. 55