One sunny day Berkley Button Nose, a Burmese cat, gazed into the fishpond at the back of his place and decided to set himself up as a detective inspector to offer his services to the local pets in the area. So that he could communicate with his client's owner, he collected any written material he could find - junk mail, the electricity bill, magazines and scratched out the letters he needed, pasting them down onto butchers paper then delivered his note to the backdoor of his client's place with a dog's bone he had snatched from the dog next door. Most of his cases were about telling the owner to change their pets diet so it was more interesting for them or being called by a different name; the problem that stumped Berkley again and again was he got his b's, d's, q's and p's mixed up because he could not work out which way the stem of the letter went - hence his notes always had spelling mistakes.

Then one day all the local pets in the area bring Berkley notes of words of wisdom they had received from someone called Mao. What does all this mean and who is Mao? Why were they given to these pets in particular? The most difficult case that Berkley has ever had has begun. He must find out who Mao is and what all these words mean.