Myth and legend surrounded Colonel Fawcett for most of his career. Many members of his family, including his wife Nina, were caught up in the popular occult movements of the early 20th century. The Fawcetts were avid believers in the Theosophy Movement founded by a Russian woman known as Madame Blavatsky. Members of Theosophical Societies were convinced that hidden cities existed all over the world where “enlightened” men and women foretold prophecies that would benefit all humankind.
Don’t judge them too harshly. You’ve spent time on the Internet. People still believe crazy ideas. “Hollow Earth”, anyone? (Note: this is italicized in the original quote)

The Fawcetts may have taken their beliefs a little farther than most. Percy and Nina believed their son Jack was actually one of these enlightened savior people and belonged in one of the hidden cities. That is why Jack was on the Amazon expedition. Colonel Fawcett was searching for the ancient lost city of “Z”, which he thought was one of Madame Blavatsky’s fabled utopias. The expedition and its eventual disappearance were widely followed by the news media in Britain and North America. Many rescue teams and other explorers have since tried to uncover what happened without success.

It'd make more sense for this to be the Failbetter collab than not, at this point, but I can't find any indication that they're working on it either. Drat.

Enthusiastic Urchin: the Postman's Pleasure
Suppose we could send you small and surprising somethings through the real-world mail every two-three months - physical Fallen London newspaper clippings, coins, or tiny trinkets, for instance. Would you be interested?
(This is not related to any rumours about possible Failbetter projects which may have been in the news lately.)


Count that as confirmation?

Considering that Failbetter is currently devoting most of their time to Sunless Sea, I find it difficult to believe that this is the FB/BW project. It's still /possible/, though, and I really hope it is.