I have opened up about 5 invitations per NPC and all I've gotten is Anthony drunkenly mentioning inspector Thorpe, how do you progress in this plot?

: You have to open up the invitations in a specific order, and then refresh on the dancing page for every NPC to get the full conversation. You can find a full guide to the plot here, but the basics are:

1. Open an invitation (starting with Cassandra's)
2. Refresh the dance page until they stop saying anything new (there's four different screens for each NPC)
3. Move to the next NPC's invitation

And when you've done the last NPC in the list (Abigail), you can go talk to Thorpe and he'll give you the next location. =)

Hope this helps!

To expand on what said, the order you need is Cassandra, Georgiana, Boudewijn, Anthony, Abigail. There is a thread here that has all the steps for the plot so far.

[edit] Missed the fact that also posted the plot thread facepalm

Ahh thank you so much! I had no idea you were supposed to refresh the page so none of the clues were making any sense. Thank you both so much!