This is, in the considered opinion of his publishers, the finest detective story ever written by Rex Stout and therefore one of the very best ever written by anyone. As a new peak for the old master, it provides an occasion to celebrate an outstanding career, as well as a new challenge to the wits of his fans.

A very rich woman comes to Nero Wolfe and Archie Goodwin, claiming that she is being harassed by the FBI. She reports that agents are following her and members of her family, her wires are being tapped, and her privacy is being otherwise invaded. She demands that Wolfe help her to find relief and offers him the largest retainer he has ever seen.

Wolfe, with some hesitation, takes the case and quickly encounters a murder about which members of the FBI may know more than is apparent. He also soon finds himself in a direct encounter with FBI agents under highly questionable circumstances.

Never before has Rex Stout written a book more perfectly plotted or one with a denouement so skillfully arrived at.  Published in 1965. 
synopsis source:   nerowolfe.org