i don't know if i have an older version of the scenario or something but there is no cave there, and there is no node in the outdoor section corresponding to any special that might be there...
oh, i was able to leave without even leaving the estate... still didn't find a cave or conversation trigger, all i needed to do was put a stick on the brazier.
i just got to that point with a group that had krug... no such conversation, i checked the editor, no trigger for such a conversation... are you sure it isn't some other place you are thinking of?