... and I'll get back to that later.
John Brooks is being coached by Ernest Stone in all of the things that long lost and ousted heir of the family, Caleb Stone, would have known if he was still alive - facts about the family and childhood memories. Brooks then appears at the Stone mansion and presents himself to Sophia and Ninevah Stone as a friend of their deceased nephew, Caleb, who knew him in the orphanage and into adulthood.
What actually happened is that Caleb was the Stone sisters' nephew, but his father died before he was born and his mother could provide no proof that she and the father were ever married, so at a young age he and his mother were cast out from the family home by the Stone sisters' father and disinherited. When his mother died he was placed in an orphanage, and that is where Brooks says he knew him. I know this all sounds so very weird 60 years later, but you have to remember that at this time no well-dressed person left the house without a hat either, and out of wedlock children were considered shameful.
So Brooks is always adamant he is NOT Caleb, but he knows so many details that Caleb knew that the Stone sisters become convinced that he IS Caleb and go to Perry Mason to change their will to make Brooks their heir. Perry knows he's most likely dealing with an imposter, but the problem is that the imposter is making no claims. It truly is a cunning plan.
But Brooks does have a conscience, and the Stone sisters are being so warm and kind to him that he has second thoughts that his partner in crime Ernest does not want him to have. The two fight and Brooks hits Ernest in the head. Ernest is OK when Brooks leaves the room, even talking to him, but less than five minutes later one of the elderly Stone sisters says that Ernest is dead, and Brooks is charged with the murder. So now the scalawag is Perry Mason's client.
When I say that Mason could be subversive, the final twist is very clever and uses a plot device the implications of which probably made the entire state of Mississippi faint dead away at the time. What do I mean by that? Watch and find out. This is truly one of the best of the series.