A young woman anxious to marry despite her uncle's objections is suspected in killing him.
The high points in this one are the funny and smart interactions with the police inspector by both Perry and Della, hip facial expressions and even a mini-legal lecture in its own right. I think what ends up not working successfully are just too many improbabilities. The idea that Nadine would steal cyanide to possible kill herself is far-fetched. The family doctor's bungling of the cause of death simply chews up time and doesn't go to plot. And, who needs a psychiatrist that pumps you with sodium pentathol and grills you about a possible murder (that had not been suspected previously) while you're recovering in a hospital? As per usual, there are about ten other twisting and somewhat related relevant things going on, but some don't quite meet a plausible motive for murder. The best legal lessons here concern ethically recovered evidence, the court room theatrics are a let-down, to the point that Mason himself reverses his own plan to have a taped confession withheld.
All-in-all, while this is yet another example of a "Perry Mason" episode that makes you pay attention at every turn, and generally makes the most of its complexity, the final resolution disappoints in every way except confirming the early theme that "you don't owe anything, everything is even."