This note contains spoilers for the book.

A murder case set among post-war price controls and industrial politics. The head of the Bureau of Price Regulation is killed at a meeting of the National Industrial Association.

It seems pretty clear that Stout is solidly behind the government controls; the NIA members shown tend to be self-centered and greedy.

The plot hinges on dictation cylinders, and the title comes from the key cylinder on which the dead man explains what's going on.

We have the usual plot element of people with secrets which have nothing to do with the murder, and a level of distrust between the two political sides which makes it impossible for them to behave sanely. We also have an additional murder along the way (if I ever find myself in a Nero Wolfe novel, I'm getting out of town fast).