From The Perry Mason TV Show Book
James Frazer has a motive for murder. He wants a divorce and his cheating wife won't give it to him. To top it off, she's been stealing the plans to his invention in order to bait her engineer boyfriend into sticking around.

Frazer skips town for three months to cool off but comes home to worse problems than he left. His wife is murdered in his office on the night of his return. He has the only key to a unique slit-type burglar-proof lock that he invented.

The police think the case is cut and dried--until Perry takes over.