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.
| Actor | Role |
|---|---|
| JJohn NesbittNarrator | Narrator |
 Marjorie KaneNot listed | Not listed |
 Nestor PaivaMail Order Crook | Mail Order Crook |
 Jo Ann SayersLeading Actress | Leading Actress |