Everywhere and nowhere all at once, the clock strikes the same hour. And everywhere and nowhere all at once, people familiar with the Nexus disappear, in the middle of whatever they were doing.
And they appear here. Seated at desks (or standing, if a desk would not hold them) in a cold, windowless room with cinder-block walls and heavy, locked metal doors, a blackboard on the wall before them and a teacher's desk before it, empty.
Their clothes are gone, as are any weapons or other items they keep on their person. Instead (if they usually wear clothing) they find themselves clad in black fatigues, a smooth metal collar around each of their necks. Even more unnerving, to those of them that rely of supernatural or technological senses outside the human norm... is the sudden silence of those senses. Stripped from them, or perhaps just deadened.
Behind those doors, there is silence.