The Drunken Lizard Pub

I would love to find the mithril that blacksmith is talking about...except that the only downstairs in my home village that I find is blocked off. There's obviously more to explore in that cellar, but there's a switch (obscured by walls) and a chest (also further blocked off) and, well, call me stupid but I just can't figure out how to get there.

Is there a hidden door that my piddly Perception stat cannot find?

IIRC, there's a pressure plate somewhere that opens up a doorway when you stand on it.