Bain's career peaked when she won three consecutive Emmy Awards portraying the quick-witted Cinnamon Carter on the popular espionage series "Mission: Impossible" (ABC, 1966-69) opposite then-husband Martin Landau. The two quit the successful series over a contract dispute and her work has been sporadic since. Apart from a handful of TV-movies, often featuring Landau (e.g., "Savage" NBC, 1973), Bain also acted opposite her most regular leading man on the sober, syndicated sci-fi series, "Space: 1999" (1975-77), as Dr. Helena Russell. After "The Harlem Globetrotters on Gilligan's Island" (NBC, 1981), Bain, now divorced from Landau, practically disappeared from public view for several years. She turned her attentions to the stage and became active in the L.A. theater scene in plays at small, prestigious venues like the Los Angeles Theatre Center (LATC). While Bain did some episodic work in the late 80s on "Moonlighting" and "Murder, She Wrote", she was more often noted for her stage role and her charity work.
Bain had made her feature film debut with "Mission Impossible vs. the Mob" (1969) a big screen spin-off from the TV series. But no other roles followed. She returned to feature films after a two-decade absence in the black comedy "Trust Me" and the drama "Skinheads" (both 1989) and in "The Spirit of '76" (1990), produced by her daughter, Susan Meredith Landau.