A cutscene occured where I teleported into a room with a tower of chairs and a rotten dude sitting on top. His yellow cloak came off, and swirled over my head. Then I got a message saying that I Invaded (insert player's name here) realm or some such, as a black phantom (even though I'm quite sure I used the blue stone??). But I couldn't go anywhere. The only exit out of the room had a fog gate that I couldn't activate. So after running around for about 5 minutes trying to figure out what to do, I gave up and left using the white stone.
So my question is, wtf just happened? I looked all over the Demon's Souls wiki and this isn't properly explained anywhere.