> The Haunted Inn is infuriatingly hard, isn't it? You'll notice in the chest room that there are a few commands available to you that aren't available everywhere, so try them out. If that doesn't help, post your inventory so we can have a clearer idea of where you are.

Okay, I had another look, and solved it.

Ironically enough, I think my trouble was an artifact of the AGL implementation - despite the chest being described when I enter the room, the necessary option for dealing with it didn't show up until I did a "look" move to confirm its presence. (Similar things happen to the jewel and metal detector.) This led me to dismiss that command as being on the wrong track.