The players did. Or rather, they decided to go after a cult doing creepy things, we did free form roleplay where they investigated where that cult my be by contacting a source in Six Towers (a neighborhood of Duskvol). From there, it was determined in play that the cult was there and the source knew where they were, but needed payment (the fortune roll was mixed). So, I decided that the source wanted something stolen from the cult's location in addition to what the PCs wanted to accomplish, to pay for his information. I then looked over the neighborhood description for Six Towers, saw Lord Scurlock's abandoned manor was a landmark, and pitched it. Here's the lore on the Six Towers neighborhood:
And here's Scurlock's Manor:
This is what informed the decision to use a cool landmark from the game -- "Bring Duskvol to life" -- and lean into the haunted nature of the neighborhood and Lord Scurlock's past -- "Paint the world with a haunted brush." I mean, haunted manors are solidly within scope of the game. Plus, the cult they were seeking had occupied play for the previous few sessions -- it didn't even exist at first, but the PCs' failures led to the addition of a cult, then the kidnapping by the cult of one PC's ally (a ghost), and then a demon got involved wanting this issue closed (am entanglement roll of "demonic notice" at a time where it fit perfectly), so the crew had a lot of motivation to do this thing. This entire quest line started with a job to recover some sets of alchemical notes that were driving alchemists mad (a rolled score, when the crew went to one of their contacts for a job). Everything else snowballed from there, as the system is built to do -- create complex stories from simple inputs and play.