Initial information: The action of the prologue takes place in 1 ABY, and the plot itself implies that Shmi did not die on Tatooine a short time prior to the Clone Wars' outbreak.
The dark chamber was not either a spacious or a well-maintained place. Much as bricking was visible here and there, the room's major space rocks that formed before ages in a way so that they now co-existed with the trunk of the huge, ancient oak upon the moon of Endor.
It was a cave, indeed. That term, however, fell out of use many years before, at the time when a Sith lord of Dath Bane's doctrine arrived there, more specifically. Since then, it had been a temple.
Now, two figures were now breaking through the darkness. One, whose face remained covered with a hood, undeniably belonged to a petite woman, while the other — to a massive man, who wore his face covered with a mask. Both of the persons were sitting opposite to each other, and the closer one found oneself to them, the clearer it would become that a serious dialogue was being arranged.
"Shmi", the man spoke with his helmet-modified voice. "The time has come for your ultimate trial."
The woman did not respond, as though awaiting a sign from the man.
"It is time that we revealed in front of the Sith and the remaining handful of the Jedi", the masked figure continued.
The woman slightly raised her head, emphasizing a range of wrinkles around her face and other marks pointing to her elder age.
"Not many of them have lasted out the eighteen years of the purge", Shmi spoke.
The man did not leave a comment on her words, continuing the speech of his instead.
"It is time for us and our Xithan neighbors to go out of the lodge. It is time for the Sith to end."
"True", the woman agreed. "For a thousand generation of their existence, the Sith wasted the power they were given, as they're wasting it now by concentrating in two people only."
The masked person inhaled a breath, which resulted in his helmet releasing a white gas from under the bottom of it. Shmi knew what her speaker meant.
"Do you think we need him?", she asked.
"Yes", he said. "Your son wields far broader horizons than his master does, in the light of which there is a probable chance that he will join us by reasons of the bond that joins you both together."
"He'll either join us or die, master."
Summary: In 1 BBY, in the Endor Sith Temple, Shmi Skywalker and her mysterious master discuss the plan to reveal the Altersith Order to the Sith and a remaining handful of Jedi. The master intends to involve Shmi's son, Darth Vader, in the plan.