From The Perry Mason TV Show Book (Revised)
Dr. Blane's son-in-law Jack Hardisty embezzled $100,000 from the good doctor and is trying to blackmail him for more. Blane hires Perry to put a stop to Hardisty's misconduct. But before the lawyer can swing into action, Hardisty is found dead, and Perry must defend the doctor against a murder rap.
Notice the old-style split screen used when Perry is talking to his client on the phone.
Correction to the Summary: Jack Hardisty did not embezzle $100,000 "from the good doctor", he stole the money from the bank where Dr. Blane had gotten Jack the job. jfh 20Jun2018