The Holders of the Shore had infiltrated the cult of the sea god to such an extent that they managed to get agents into every single notable human dock and port in the Old World and were both numerous and organized enough to simultaneously sabotage every single human major port and dock in the old world with the notable exceptions of Kislave and Sartosa . the larger the number of people who know a secret the more likely it is to get out and the bigger an organization the more likely it starts to leak , that such a massive number of the holders of the Shore were operating on such a massive organized scale within the sea god's cult means that either that the Foamborn are incredibly incompetent or the Foamborn have been thoroughly subverted after all how else could a massive clandestin undertaking involving so many people go down without anyone being the wiser
Wow. So that's another paranoid argument you're making there: If this catastrophic event has occurred than that automatically means that multiple other catastrophic events have occurred.
What if the Foamborne were only looking for individual cells of the Keepers of the Shore and this new organization is not connected to those?
What if this terrorist organization grew from a single terror cell deciding not to continually split into two, but instead to lie low and bide their time so they could do what they think of as Manann's work properly?
What if they sold out the cells that refused to join them to the Foamborne to hide their own tracks?
What if they lived in isolated churches in places where a Priest of Manann was needed/wanted, but ships weren't?
All of these actions are things real life terrorist cells have done. I have yet to see an argument for not letting the Foamborne do their work that isn't a paranoid one.
I don't understand what you're trying to do here.
If the cult does the investigation, and even if they roll well or not, they won't really tell us everything. If we want to get to the bottom of why the attacks Holders of The Shore committed were so successful, we should let the Witch Hunters off their leash. Considering the fact the whole of The Old World was affected it makes more sense for The Witch Hunters to do their job.
I don't think we can actually do that. Voting for letting the Cult do the investigation is letting them do all of it.
We don't need to know everything that goes on in this quest. More importantly we can't know everything that goes on in this quest unless we have
@torroar's notes on what is going on in this setting. We are not getting those because it will make this quest a lot more boring. In fact one of the traps in Warhammer (both Fantasy and 40K) stories is that a character gets too paranoid and wants to know everything without trusting anyone.
The job of the Witch Hunters is to hunt proscribed cults. The Keepers of the Shore are now a proscribed cult:
Shockwaves have torn through the naval trade due to so many ships burning, or otherwise being damaged or destroyed, while the true Cult of Manann is working frantically with all authorities to root out these decentralized cells of what has been openly declared as of this year to be a heretical cult subject to extermination by Grand Conclave. Any found to be a member of the 'Holders of the Shore' are to be interrogated and executed, by assent of all Cults represented at the Grand Conclave. The newly chosen Matriarch of the cult, Maghda Sprenger, personally drowned the members of the cell that resided within Marienburg in front of witnesses, before declaring her intent to exterminate the entire heretical sect within her tenure. A powerful statement, alas one that is couched in the knowledge that ships and port facilities across the coastline have been so savaged.
And as a proscribed cult they fall under the responsibility of the Witch Hunters. So once the Foamborne are done we can still let loose the Witch Hunters.