This John Nesbitt's Passing Parade series short highlights the film preservation efforts of the Museum of Modern Art in New York. Several scenes from early newsreels are shown.

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.