Few know of this place, and far fewer know of its location. This is a good thing, for nothing wholesome comes from here.
An ominous emblem begins appearing in tapestries, paintings, engravings, streets, etc. across the town or city in which the players are staying.
Last night, your buddy was thinking about calling one of those crazy psychic hotlines, he was really depressed, his girlfriend dumped him, and he wanted some good news. You know they’re all a scam, they give you some advice that could apply to everyone and a large bill to boot. You told him to go for it.
But now he’s missing. All you have is his cell phone, and something is wrong with it. You found it in your toilet today. Yeah, your toilet. It’s got all his old numbers and a few you don’t recognize. You tried to call some, but all you got was a what sounded like a bunch of voices muttering at once. What the hell is going on here?
A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.