Don't Know How to Advance in Soul Trade Storyline

I’m trying to be vague because it’s fate-locked content, but I really need some help on the Soul Trade Storyline.

I have a Merchant of Souls 5, and the Hell’s Fence option in Ladybones Road. Where do I go to get souls?

I have NO idea how to advance in the storyline. Where do I go? Do I wait for a card? Do I need the special item equipped? I haven’t done anything with this storyline for over a month because I haven’t seen any opportunities to advance in it. Thanks in advance.

Here is a thread with the answers you want. You’re finished with the storyline, by the way, though there are some opportunities here and there to put your Spirifer’s Fork to use.