This book was published in 1968. The third in the series. It is a little gritty. I like seeing into Qwill's life when he still lived "Down Below". I have read most of this series (28 books). She wrote the first three and then took an eighteen year hiatus before book 4.
The mystery is pretty light, but you can find the clues if you are looking. I like the cat angle. Koko and Yum Yum have a certain way about them that cat lovers will gravitate towards.
Qwill's pipe smoking is very dated, but I can over look it due to the age of the book. It is somewhat distracting, though.
This is a good one to start with, as it introduces Mrs. Cobb. I just LOVE Mrs. Cobb!!! Of course it would be even better to start at the beginning with The Cat Who Could Read Backwards.