The plot twists for this mystery start appearing practically from the second page, so it is hard to describe the plot and make the description comprehensible and short at the same time. I think the former would have to be sacrificed, sorry.
A crippled man came to Perry Mason with an unusual problem. He was a caretaker for a rich guy practically all of his life, so when his boss died his will stated that the heir should keep the caretaker at his job until he is unable to perform it (we are talking about just living in a house - not exactly a physically demanding job). The heir is fine with the provision, but he strongly insists the caretaker's cat - his only true friend - has to go; he even threatens to poison it in case the poor animal remains in the house. So the caretaker want Mason to protect the cat.
I could not resist using an image of Grumpy Cat; I love the guy.
And thus the famous lawyer has a cat for a client.
He took the case practically out of pity only to be mixed up in several murders, innocent (but stupid, let me tell you) people accused, and having to do his magic in the courtroom. The plot twists keep on coming.
What is unusual about this case is the number of dead bodies: a typical Mason's case only involves one - this time it is more; I am not giving the exact count. I like all the twists, but the very end was a little underwhelming for all the buildup. The trademarked Mason's courtroom shenanigans that go on for pages and pages only lasted three ones here and resulted in a quick, but not quite satisfying conclusion.