The Father Hunt by Rex Stout

Lilly Rowan is a good friend of Archie's. One day, her secretary, Amy, asks Archie if he (not Nero) can help track down her father, a man whose name she never knew. Archie demurs, saying he only works for Nero and that Nero is very expensive. Well, Amy comes up with the money to pay Nero's salary and the boys are off on a case that tracks back twenty years and overlaps with the death of Amy's mother.
A good Nero Wolfe book. 

Three stars

Follows Death of a Doxy

Followed by Death of a Dude

This book came out May 28th, 1968

Audiobook borrowed from Libby

Opinions are my own