The Dink Network

Help! In mini-castle quest, I can not find Josepth's cup . The smuggler said it was in a cave under the dolman north west of town. I talked to that rock, bombed it, tried to climb under it. Maybe the smuggler was lying? Also tried the dolman where I entered this domain, to no avail.
Where can I find the golden cup?

Hit the dolmen with a weapon or magic, talk to it, ask for help, then bomb it and it should work. If it doesn't work, try bombing it from another side.