[He'll look around, puzzled, clearly trying to find the source of that voice.]

Where is that voice coming from... Ahh.. [His gaze lands on the bookmark, and he leans in to pick it up, where it's resting on a table at his elbow. He'll study it, intrigued.] I take this is... something like a telephone, only with a visual capture?

It comes as no surprise that you've not heard of them: they are a secretive sect who remain out of sight, guarding strange relics and eldritch tomes.

The Central Library... dare I ask, to what it is central?