Opening the entrance to the Order's underground tavern in Phantom Blade Zero took me longer than I'd like to admit, but it's required to continue progressing through Pangzhen during the Town of Death quest.
In the wine yard behind the tavern building, Soul will note that the pavilion's floor on the right is hollow—this is where the secret entrance is, so you'll want to head behind the pavilion and smash the big black jar, as in the video above.
