I would like to ask a quick question before I begin speaking about plot: what is dude? Please do not use a dictionary. I will explain this in terms of popular movies and this would probably be the first time I tried to describe a book using unrelated
movies. So the first idea of dude is probably this one:
The second idea coming to mind when somebody mentions the word is usually the following:
The definition the book uses however is this:
In other word, city slickers.
For another bit of trivia - very amusing but having almost nothing to do with the novel - have the following question: how do you call a female dude? The modern English slang uses either the same dude, or much better sounding dudette. Archie Goodwin's girlfriend Lily Rowan calls herself dudina here.
Back to the novel: Archie Goodwin (one of the dudes) came to a Montana ranch owned by Lily Rowan for a quiet vacation. By no fault of his, murders follow him no matter where he goes. This time one of the dudes on a nearby ranch was killed by seemingly inept shooter and Lily's foreman was accused of the murder. He does not have an alibi, but he does have an excellent motive. Archie is one of the few people who did not believe his guilt, but his doubts are based on his knowledge of the accused and the fact that the former is an excellent shot.
Archie sets up to do what he does best: investigating. Unfortunately he is a dude and no locals bother to talk to him much. Even the other dudes follow locals' example. Archie is stuck, but he refuses to budge. His boss, having received a letter with explanation why his trusted sidekick will not show up in Manhattan any time soon, does the unthinkable, something he did only twice before: he leaves his steady comfortable daily routine and comes to speed up the process of investigation.
And so Nero Wolfe comes to Montana. Knowing about Archie very limited (to put it mildly) success with asking questions about practically anything, he is ready and loaded for a bear. When Nero Wolfe is ready high-ranking politicians get bothered, a lot. When high-ranking politicians get bothered, things get done, quick.
What was really surprising for me while I read the novel was the level of corruption in the quiet countryside which put the one in a huge megalopolis that is New York City to shame. At least in Manhattan people had to pretend they are corruption-free while Montana politicians had no need for such pretension. This is probably the first time Archie got beaten up by the police with the good old excuse of "resisting arrest".
The plot has enough twists to put any labyrinth to shame. Rex Stout was well into seventieth when he wrote it; his age had not affect his writing abilities any.