It's always a bit of a gamble when Stout sets our heroes Archie and Nero to venture into the realm of the truly classic mystery - a big house full of the wealthy and powerful, people hiding behind curtains, disguising themselves as each other, getting strangled in the parlor - but this one pulls it off by the neat trick of having Wolfe both leave the brownstone unexpectedly (to Archie) and return to the brownstone unexpectedly (to everyone else.)  Also, quite unusually for a Wolfe mystery, it's all more or less played fair - Wolfe has to obtain particularized proof of a specific fact that is only strongly implied by the text, but we don't. It's just a hint, and if you think it through the reader can solve it. But with such a big tangled cast and a series of bizarre events it will be a pleasure just to try.