This is book 46 of the "Nero Wolfe" series.

This note contains spoilers for the book.

Described on the cover as "his last case". That's compatible with the copyright date.

Once again Wolfe's involvement with Rusterman's gets him in trouble. A waiter there says somebody is going to kill him, but won't tell Archie. He's blown up by a bomb he brought himself while preparing for bed in the South bedroom of Wolfe's house. This turns out to relate to another murder that's had some notoriety, and then a third murder happens. Yeah, somehow I managed to grab the two Wolfe books that involve bombs almost next to each other.

I even noticed some of the clues, out-of-character behavior as it went by. (I don't read these as problem stories primarily, and the problems and their solutions are not what sticks in my mind when I read them.)

All of which is built up into a really major smashing climax. Not a bad note to end the series on at all. Though it does bother me that Archie must be more than 65 years old in this book (it claims it's set in 1969). But we know that West 35th Street is an island in the sea of time already, so that's no big surprise.