Perry Mason has dealt with the art world, orchid farms, and the theater. It's good to see a case shift to a world with which I am familiar - that of engineering.
Inventor James Frazer leaves home to work on his invention, telling his wife, Thelma, that he'll file for divorce later. Three months go by and nobody has heard from Frazer. He is partners in the Hayden Electronics company along with the Hayden brothers. The Hayden Brothers tell Thelma that if James does not return to the office in person by 5PM the next afternoon that they have the right, by contract, to buy him out at what the company was worth several years ago, about a tenth of what it is now. Later that night James does return home, but his house is ablaze and Thelma is dead inside. James is arrested for the murder of his wife, so he is in double trouble. He not only is accused for murder, he could be legally cheated out of his rightful share of the company that he helped found since he is in jail and unable to come to the physical location of the company. Enter stage left Perry Mason.
Perry gets to show his abilities in the area of contracts in this episode as he plays those (legally) thieving Hayden brothers like a violin. Della Street also shows her loyalty here, as she could have easily forced a large payout to herself and maybe not retired but had a secure retirement in the future. Given that it should be obvious by now that it is as likely for Perry to pop the question as it is for Matt Dillon to do the same for Miss Kitty, maybe that would have been the wise thing to do.
Of interest was how fascinated everybody was with Frazer's invention of the card key - he uses it on his door as a lock, and whether or not it is easily reproduceable by a novice is a critical part of the case. The card key was invented in Norway in 1975 and first used in the United States in 1978. So Frazer would have been far ahead of his time given this is set in 1960.
Recommended even if you are not an engineer.