No, not the adventure of that name but a series of rules to handle situations where adventurers have the corpse of some mutated rat and insist it's a "rat man, a skaven!" Rules that work towards keeping the "truth" suppressed. Borrowing a bit at times from Cthulhu concepts (skaven are like the mythos).
Everyone knows there's no such thing. Extra challenge die on all attempts to convince/motivate based on "the rat people are doing it etc. etc." - e.g., "you must send soldiers, the skaven are going to attack", "don't eat it, the skaven have poisoned it!"
You know what you're saying can't be true even as you're saying it. Suffer 1 stress every time you proclaim "it's the SKAVEN!" or similar to anyone who doesn't share your mad belief. Add following to all such rolls: comet - you get used to this difficulty and can ignore it in future.
It's awkward being around friends with these delusions/who don't admit the truth. If everyone in a group backs a declaration (takes 1 stress), okay but if everyone doesn't, then increase Party Tension +1.
One of Us, One of Us. Admitting you were wrong is very destressing. Automatically reduce stress by 1 and make a Discipline check as when rallying for more reduction if you openly admit your foolishness/error.
Any comments/alternatives?