The Denver of the Secret Nine is an admittedly tortured misuse of a fictitious book title or predicament that P.G. Wodehouse used in several stories.
From Mating Season:
And that, of course, was that. It was no good telling her that I would prefer not to touch young Thos with a ten-foot pole and that I disliked taking on blind dates. When Aunt Agatha issues her orders, you fill them. But I was conscious, as I have indicated, of an uneasiness as to the shape of things to come, and it didn’t make the outlook any brighter to know that Gussie Fink-Nottle would be among those present at Deverill Hall. When you get trapped in the den of the Secret Nine, you want something a lot better than Gussie to help you keep the upper lip stiff.
And Heavy Weather:
‘Too risky. You don’t know what that house is. There’s Lady Constance after the thing and Gally Threepwood after the thing and Ronnie Fish and … well, as I said to Monty Bodkin this afternoon, a fellow trying to smuggle that manuscript out of the place is rather like a chap in a detective story trapped in the den of the Secret Nine.’
For the moment, it’s the provisional name of the Denver chapter of The Wodehouse Society.
The Denver of the Secret Nine 