Stout, Rex -- Death of a Doxy (1966)

Orrie Cather has got himself embroiled with a young woman from the chorus line. Now he wants to marry someone else, and he calls on Archie to enter her flat to try and find some compromising letters. Archie finds the girl, Isabel Kerr, dead on the floor, and high-tails it out of there. Cather is picked up by the police, and the question is raised in the Wolfe household: did he do it? Luckily Saul Panzer decides the result in the negative, and he, Archie and Fred Durkin are put to work looking for evidence to clear their colleague.

There are long periods of frustration, and a bout of gunplay, before the case is broken -- with the help of Julie Jaquette, Isabel's friend and the only woman to sing to Nero Wolfe in his office and get away with it. Alas, it is stupidity on the part of the murderer rather than ratiocination on Wolfe's side that does the trick. Entertaining, but not classic Wolfe. 

Jon.