Unseen Guardians (1939)
The "unseen guardians" of the title are the Postal Inspection Service, which investigates mail order racketeering; the Underwriters' Laboratories, which are shown testing electrical equipment, fire extinguishers, and large floor safes; and those who run orphanages, who assure that the children in their care are placed in proper adoptive homes.
Directed by Basil Wrangell
Written by George Wallace Sayre, Doane R. Hoag, Samuel H. Chain