What if Drusila is using the soul jar to jump from body to body?
We think she's been killed, but she's the true villain.
Thoughts?
Personally, I don't think so, because of the 100 feet and line of sight limitations.
My suspects now are the White Dragonborn sorcerer (commiting the murders) and the top-hatted man/Fel (stealing our talismans, delivering the letter), but I think there is someone behind these two, this mysterious master. I could imagine it's something living in the tunnels and caverns of the Riverveins, or in the sewers - or maybe this is just where the base of their cult is located. My first thought was that the top-hatted man/Fel could be a warlock, and since he has this sea creature skeleton pinned to his hat, his patron is something/someone sea-related.
If the Dragonborn had murdered Drusilla, and Fel had stolen our talismans, finding them on Drusilla's houseboat could maybe prove that these two work together.
I don't think I want to go back to our home. Even if the murderer (who I think most likely was the Dragonborn) did not use a spell to impersonate us before murdering Drusilla, somebody might have noticed that we rowed to the houseboat. Either way, we are the prime suspects. I think the prophecy made by the Drawing Tree was indeed quite literal, I think the Dragonborn tries to frame us for murder by magically impersonating us. I'll trust that tree .
Both the Underground Passageway and Riverveins Entrance feel like traps, so there's only the Sewer Keep left... I hope we still have some time left. I'm not brave enough to confront the Dragonborn or Top-Hat-Man alone, and I think I need more information on the sewers and everything underground, so I think I'll vote for Sewers Keep.