I just can't agree with the reviewer who commented that the cat series was growing weaker. In fact, I think this was a bit better than the last several preceding this, partly because of the new surroundings.
Granted, the plots of the cat books are sometimes a bit weak, even outlandish. And the details of every last thing Qwilleran had for breakfast, lunch and dinner can be a trifle tiresome after the tenth time or so, especially when the same sort of detail is applied to the cats' meals and snacks.
But I can tolerate all those because the characters seem real and because the atmosphere is so carefully drawn. In this case, for example, we have the building owner, the "countess," with overtones of Miss Havisham telling Pip (or Qwill, in this case) simply to "Play." And then there is the apartment building, the Casablanca, with its rickety elevators and other signs of age and disrepair. I feel that I actually know the countess and can smell the Casablanca or find my way through the hallways in the dark.
One has to go by the sum total in evaluating a book, i.e., the credits minus the debits. That being so, I have to give this a solid recommendation as I look forward to the next in the series. The perfect mystery? Not at all. But pretty good.