The Case of the Baffling Bug Perry Mason : Season 9 Episode 13

Tryon Laboratories hires the Drake Detective Agency to protect their latest formulas. In spite of Paul's best efforts, there is a leak in security and some top-secret information is stolen. One night, Leigh, an undercover agent working for Dr. Scranton, the head of the company, calls to say he knows the identity of the spy. Scranton and Paul rush to the laboratory only to find Leigh dead, floating in a vat of water.