Wikipedia
O.S.S. was a Buckeye Productions and Associated Television co-produced wartime television drama series.
It ran for 26 half-hour monochrome episodes during the 1957-1958 season and was distributed by ITC Entertainment and networked in the United States by ABC.
The series followed the adventures of Frank Hawthorne, an agent with the American Office of Strategic Services, who operated behind Nazi lines in occupied France.
O.S.S. is a 1946 war film starring Alan Ladd and Geraldine Fitzgerald about the Office of Strategic Services. It was directed by Irving Pichel, who would later be blacklisted by the House Un-American Activities Committee, and written by Richard Maibaum, a World War Two veteran who would later write 12 of the first 15 James Bond films.
Richard Maibaum, a former Broadway actor, also narrates the film.