The series was loosely based on the life of
Herbert Philbrick, a Boston advertising executive who infiltrated the
U.S. Communist Party on behalf of the
FBI in the 1940s and wrote a bestselling book on the topic, ''I Led Three Lives: Citizen, 'Communist', Counterspy'' (1952). The part of Philbrick was played by Richard Carlson. The "three lives" in the title are Philbrick's outward life as a
white-collar worker, his secret life as a Communist agent, and his even more secret life as an FBI operative helping to foil Communist plots.
I Led 3 Lives lasted 117 episodes. Philbrick served as a technical consultant, with Carlson narrating each episode. ==Main cast==