Fer-de-Lance is the first of the Nero Wolfe books. As such, the formula had not been fully developed. I am a big fan of Rex Stout's Nero Wolfe books and the magic doesn't come from the plots. It is entirely built around the personalities of the characters in how they intersect/clash.
Stout brilliantly blended together the worlds of the classic European detective and the American hard-boiled detective. Nero Wolfe is literally an armchair detective who can't be bothered to do things like with the house or stand up. (OK, that's kind of an exaggeration. He does end up getting hauled out of his house enough that it starts to feel like a cliche) His assistant and partner in all but name, Archie Goodwin, is the snarky hard-boiled detective who near it's the stories and actually has to go out and get all the clues.
The mysteries are pretty good and even tend to be nicely grounded without too many outlandish coincidences or gimmicks. But the real reason I read the books is for Wolfe and Archie's bickering.
Fer-de-Lance is not one of my favorite books in the series. Stout was still developing the characters, although Wolfe starts off as eccentric as he would ever be.
When I first read the book, not quite twenty years ago, two things in particular struck me about the book that I did not like.
The first was the murder weapon. A poison dart that is shot out of the handle of a golf club when it hits the ball. That seemed pretty far-fetched, particularly in comparison to a lot of the later books. And I'm still not a fan of that.
Second is the climax of the investigation. Which, I'm going to partially spoil, by saying that Wolfe gives the heads up to the murderer, giving them the chance to commit a murder-suicide instead of getting arrested. Archie gave the explanation, which I initially accepted at face value, that he did it to get out of having to be a witness at the trial.
However, rereading the book, I realized that Fer-de-Lance is more
of a noir work than most of the Nero Wolfe books. The ending fits the dark and gritty and cynical sense of justice of a noir work and makes it clear that Wolfe's motivations are far more complex than just wanting to stay at home.
Fer-de-Lance still far from my favorite book in the series. It is also not a book I would recommend for someone who has read the series. However, my realization that it harkens towards a different genre has made me appreciate the book more the second time around.