7 Trouble and Interruptions
Here is probably one of the trickiest parts, hence I'm not gonna tell you about it,
MTG's Mark Rosewater is. While you should absolutely read the article, here is the quote I'm into "A knob is a component of a card design that can be changed." The concept of a knob isn't something that is intrinsic to the game of magic, it's a mechanic present at design time. Say a card is too powerful, you can crank up the drawback knob to balance and it keep the game fun. Magic cards are printed onto paper, which doesn't change often and therefore once the game becomes real, the knobs are fixed.
However this isn't printed on ink, so you can twiddle the knobs as much as you want at play-time as long as you know where they are. Pacing is the most important part of a good story and you're trying to tell a good story damn it. So these knobs need to keep the pace up. Given that they story from the previous posts involves crime, the presence of police is an easy knob. The attention of the police and where the players can comfortably go. We also have two other plot threads, the author committing a murder and a ritual occurring. These are fixed things that will always play out, on your timeline.
Which brings up an interesting point. You should know how the story would end if the players were to do nothing. This is a truism, as you know the locations, events, characters, and the motivations but also plan. The more comfortable you are with how a story would work, the more quickly you can incorporate players.
8 Resolution
The guidebook provides 3 resolution types:
Closed Loop - The characters resolve this incident, but the greater threat is not answered
A Greater Threat - The characters end up being pointed towards a greater threat that requires immediate action
Deeper Mystery - The characters reach a dead-end. Things are learned but nothing is understood
This seems like peak Delta Green, peak everything is bad, peak you accomplish nothing. Your reward is that you don't die today. Pretty much each of the terminal nodes of the store allow for any of the three endings. The Closed Loop and Deeper Mystery are the easy outs as only A Greater Threat requires further writing on your part. Make sure to throw some extra weird unexplained shit in if you do the Deeper Mystery.
Side Note: Weird Shit
You, as the storyteller, should have a greater understanding of what is going on than the players, but even you don't have to have all the answers. You don't need to explain anything to them or provide closure. Outside of Lovecraftian stuff, vagueness usually doesn't fly. Hopefully the people you are playing with are into that kind of story.